feat(lanes,git): publish a repo with no remote, and read a repo with no commits

What broke: a lane on a fresh `git init` repo had no working git surface.
`statusCounts` ran `rev-parse --short HEAD` unguarded, so `gitFacts` threw
and `GET /api/lanes/:id/git` answered `{available:false}` — the Changes
panel showed no header, and `commit`/`switch` 500'd through `isDirty`.
Add lane in Worktree mode accepted such a repo and left a `failed` row
behind, and a repo with commits but no remote had a permanently disabled
Push with no way to give it one short of a terminal.

What changed:
- worktree.js: an unborn HEAD is a normal state. `statusCounts` reports
  `head: null`; `gitFacts` reads the branch via `symbolic-ref`, an empty
  subject, and a new `unborn` field.
- git-ops.js: an 11th write, `publish` — `remote add origin -- <url>` then
  `push -u origin HEAD`, only with a commit (ENOCOMMITS) and NO remote at
  all (EREMOTEEXISTS, so it never re-points one), the url allowlisted by
  `validateRemoteUrl` (https without userinfo, ssh://, scp-like; refuses
  local paths, file://, ext::, fd::, git://, http://, leading `-`:
  EBADURL), and `origin` removed again when the push fails.
- POST /api/lanes/worktree answers 400 EEMPTYREPO for a repo with no
  commits instead of creating a row that can only fail.
- LaneGitBar: unborn repos show "no commits yet" and a commit-first hint;
  no remote offers Publish… with an inline URL box; a remote but no
  upstream relabels Push as "Publish branch". AddLaneModal disables Add
  on an empty repo and offers "Use as a Repo lane".
- The two tests that used an unborn repo to force a provisioning failure
  now use a `feat` ref clash, since that repo is refused up front.
- CLAUDE.md rule reworded to "the boring eleven" with publish's guards;
  docs/API.md, docs/LANES.md, ARCHITECTURE.md, server/README.md, openapi.

CLAUDE.md

@@ -37,7 +37,7 @@ A **lane** is a durable unit of parallel agent work — one working directory, m
 - **Never `rm -rf` a lane.** Destructive lane operations (`reset`, `remove`, `purge`) go through `server/lib/worktree.js`/`server/lib/lanes.js`, never a raw filesystem delete — that's what keeps the three-check destroy guard and the DB bookkeeping in lockstep.
 - **Never build a git command as a shell string.** Lane git operations use `execFile("git", [...args])` with an explicit argument array (see `server/lib/worktree.js`'s `git()` helper), never a concatenated/interpolated string passed to a shell.
 - **A lane's AI Router profile is a lane fact too, and it never travels alone.** `lanes.router_profile` (nullable; null means the same as `native`) is written ONLY by `setRouterProfile`, called beside the disk write in `POST /api/lanes/:id/router/apply` — never through `PATCHABLE`. The column and the lane's own config must move together, or the row claims a router the lane's `settings.local.json` has never heard of. What is written comes from the lane row, never the request: a **claude** lane gets eight `env` keys merged into `<cwd>/.claude/settings.local.json` (`.local` because the value carries an API key; every other key in that file is preserved and a non-JSON file is refused, not rewritten), a **codex** lane gets `$CODEX_HOME/<name>.config.toml` — the layer `codex -p <name>` loads — because Codex has NO project-level config, and its base `config.toml` is never touched. Key material never leaves the server: profiles live at `<CLAUDE_HOME>/agenthub-routers/` (0700/0600), `GET /api/ai-routers` reports only `hasKey`, and there is deliberately no route that returns one profile in full. **`POST /api/ai-routers/test` sends a stored key ONLY to the endpoint it was stored against** — a blank `apiKey` falls back to the profile named by `name`, but only while the submitted `baseUrl` still equals the saved one, else `EBADKEY`. Relax that and the route becomes a way to make the server POST a saved key to any URL a browser names. **Re-pointing a lane is allowed and is not a PATCH:** the lane card's AI Router select calls `POST /api/lanes/:id/router/apply` (column + disk together, same rule as above), never `PATCH /api/lanes/:id`. **Codex's key reaches the pane through tmux's `-e` argv and is never typed into it** — `tmux.sendCommand` takes over an idle pane with `respawn-pane` for exactly this reason; a `KEY='sk-…' codex …` line typed with `send-keys` would be rendered to every attached browser, kept in the scrollback and appended to the user's shell history. Do not reintroduce a typed command line there. **And attaching COPIES a profile**, so the store stops being the single source of truth the moment a lane exists: `PATCH`/`DELETE /api/ai-routers/:name` must push through to the lanes naming it (`reapplyToLanes`/`detachFromLanes`), or a rotated key silently never reaches the lane still using the revoked one. See `server/lib/ai-routers.js`, `server/lib/router-apply.js`.
-- **The dashboard's git writes are these sixteen, and the guards are IN `git-ops.js`, not in the UI.** `POST /api/lanes/:id/git/:action` offers `fetch`, `pull`, `push`, `stage`, `unstage`, `discard`, `stage-hunk`, `discard-hunk`, `commit`, `switch`, `branch-create`, `branch-delete`, `merge`, `resolve`, `merge-commit`, `merge-abort` — nothing else. **A path in the body is never a path**: `resolvePaths` accepts only what `git status` is reporting as changed right now, which is the whole authorization story for the per-file actions (no `..`, no absolute path, no untouched file). `discard`, `discard-hunk` and `merge-abort` are the irreversible actions and all refuse to run without `confirm: true`; do not add another destructive action without the same gate. `branch-create` never switches (the reason to create one from a lane is a sibling worktree, not moving a working agent's HEAD) and `branch-delete` is `-d`, never `-D`, refusing `main`/`master`/`development`/`develop`, the current branch and one another worktree holds. `pull` is ALWAYS `--ff-only` and `switch` refuses a dirty tree, so neither can invent a merge commit or a conflict underneath a running agent; `push` pushes `HEAD`, never a branch name from the request; `commit` passes its message as one argv element. **The lane is the boundary, not the repo**: a subdir lane's reads and writes stay under its own cwd, and no read may return a `settings.local.json` (`ESECRET`) — do not add a git read that skips `lanePath`/`isSecret`. **A merge is the one history-joining action, and only because its recovery is a button too** (`merge-abort`): it starts only by name, on a clean tree, from a lane at the repo ROOT (`ESUBDIR` — a merge is repo-wide and a subdir lane could not resolve a conflict outside itself), one at a time (`pull`/`switch`/`merge`/hunk actions answer `EMERGING` meanwhile); the ref is looked up in `refs/heads`+`refs/remotes`, never passed through; a conflicted file is resolved only through `resolve` (ours/theirs, or `done` once no conflict marker is left — `stage` refuses a conflicted file that still has markers, `EMARKERS`), and `merge-commit` refuses while anything is unmerged (`ECONFLICTS`). Do not add rebase, reset or stash here: a dashboard click is the wrong place to start an operation whose recovery needs a terminal, and `reset` already lives behind `worktree.js`'s three-check destroy guard. A button that looks disabled in `LaneGitBar` is a courtesy; the refusal that matters is the server's. Reads (`/git`, `/git/changes`, `/git/log`, `/git/file`, `/git/ls`, `/git/tree`, `/git/branches`) stay unguarded like `/git` always was, and resolve their repo from the LANE ROW — `GET /api/lanes/branches` is the only one that takes a path from the request, because its lane does not exist yet.
+- **The dashboard's git writes are these seventeen, and the guards are IN `git-ops.js`, not in the UI.** `POST /api/lanes/:id/git/:action` offers `fetch`, `pull`, `push`, `stage`, `unstage`, `discard`, `stage-hunk`, `discard-hunk`, `commit`, `switch`, `branch-create`, `branch-delete`, `publish`, `merge`, `resolve`, `merge-commit`, `merge-abort` — nothing else. **`publish` is the ONE write that takes a destination from the request** (`{url}`), so it can only give a remote to a repo that has NONE: it refuses before the first commit (`ENOCOMMITS`) and whenever `git remote` prints anything (`EREMOTEEXISTS` — it never re-points a remote, so it cannot redirect a repo that already publishes somewhere), the name is always `origin`, the URL passes `validateRemoteUrl`'s allowlist (`https://` with NO userinfo, `ssh://`, scp-like `user@host:path` — never a local path, `file://`, `ext::`, `fd::`, `git://`, `http://` or anything starting with `-`), it runs `remote add origin -- <url>` then the same `push -u origin HEAD` as `push`, and a failed push removes `origin` again. That is still weaker than the AI-router "a key goes only to its stored endpoint" rule — a browser on the dashboard's origin can publish a remote-less repo to any allowlisted host — so do not widen the allowlist or let it touch a repo that already has a remote. **A path in the body is never a path**: `resolvePaths` accepts only what `git status` is reporting as changed right now, which is the whole authorization story for the per-file actions (no `..`, no absolute path, no untouched file). `discard`, `discard-hunk` and `merge-abort` are the irreversible actions and all refuse to run without `confirm: true`; do not add another destructive action without the same gate. `branch-create` never switches (the reason to create one from a lane is a sibling worktree, not moving a working agent's HEAD) and `branch-delete` is `-d`, never `-D`, refusing `main`/`master`/`development`/`develop`, the current branch and one another worktree holds. `pull` is ALWAYS `--ff-only` and `switch` refuses a dirty tree, so neither can invent a merge commit or a conflict underneath a running agent; `push` pushes `HEAD`, never a branch name from the request; `commit` passes its message as one argv element. **The lane is the boundary, not the repo**: a subdir lane's reads and writes stay under its own cwd, and no read may return a `settings.local.json` (`ESECRET`) — do not add a git read that skips `lanePath`/`isSecret`. **A merge is the one history-joining action, and only because its recovery is a button too** (`merge-abort`): it starts only by name, on a clean tree, from a lane at the repo ROOT (`ESUBDIR` — a merge is repo-wide and a subdir lane could not resolve a conflict outside itself), one at a time (`pull`/`switch`/`merge`/hunk actions answer `EMERGING` meanwhile); the ref is looked up in `refs/heads`+`refs/remotes`, never passed through; a conflicted file is resolved only through `resolve` (ours/theirs, or `done` once no conflict marker is left — `stage` refuses a conflicted file that still has markers, `EMARKERS`), and `merge-commit` refuses while anything is unmerged (`ECONFLICTS`). Do not add rebase, reset or stash here: a dashboard click is the wrong place to start an operation whose recovery needs a terminal, and `reset` already lives behind `worktree.js`'s three-check destroy guard. A button that looks disabled in `LaneGitBar` is a courtesy; the refusal that matters is the server's. Reads (`/git`, `/git/changes`, `/git/log`, `/git/file`, `/git/ls`, `/git/tree`, `/git/branches`) stay unguarded like `/git` always was, and resolve their repo from the LANE ROW — `GET /api/lanes/branches` is the only one that takes a path from the request, because its lane does not exist yet.
 - **AgentHub's git credentials are its OWN store, shared by every user of the install, and git is given ONLY that store when it holds a login for the host.** `server/lib/git-credentials.js` keeps one record per `protocol + host` under `<CLAUDE_HOME>/agenthub-git-credentials/` (0700/0600) and no route ever returns a password (`hasToken` only). `gitConfigFor` runs a network action with `-c credential.helper= -c credential.helper=<ours>` whenever AgentHub holds a login for a repo remote's host or the request carries one — the machine's helpers are left out on purpose: a stale token there would win over the typed one, and git's post-success `store` would copy a use-once token into the OS user's helper. The secret travels in the helper's env or the store file, never argv. A typed credential is accepted only for one of the repo's OWN remote hosts (`EBADHOST`), so a login is never sent to a server it was not typed for, and it is saved only after git SUCCEEDED and `remember` is set. Do not add a route that returns a stored password or a path that forwards one to a host other than its own.
 - **A lane's `tool` is a lane fact, immutable, and never read from a request.** `lanes.tool` (`claude` | `codex`, default `claude`) is set by `createLane` only — it is deliberately absent from `PATCHABLE`, so no PATCH can flip the CLI under a live pane. Every spawn path (`POST /api/lanes/:id/start`, `POST /api/run`) takes the tool from the lane row and ignores whatever the body says; the run panel's Codex-only fields (`sandbox`, `approval`, `resumeLast`) are validated against the fixed allowlists in `server/lib/pty-run.js` before they reach an argv, and the bypass flags (`--dangerously-bypass-approvals-and-sandbox`, `--dangerously-bypass-hook-trust`) are never emitted. `GET /api/run/binary?tool=` resolves the probed binary name from that same allowlist — the query string reaches `which`.
 - **A lane's card position is a viewer preference; its name is a lane fact.** The Workspace strip's drag/Alt-arrow order lives in `localStorage` (`agenthub.workspace.laneOrder`, `client/src/lib/laneOrderStorage.ts`) and writes NOTHING server-side — `GET /api/lanes` and `agenthub lanes` stay in id order, so no `sort_order` column, no reorder route, no websocket message. Renaming is the opposite: it is `PATCH /api/lanes/:id` with `{title}`, the one lane column a user now types into directly, so `updateLane` normalizes it (`normalizeTitle`: trim, 200-char cap, `null` ⇒ `""`, because clearing is legitimate — every render is `lane.title || lane.cwd`). The rule is the column-wide one, not a special case for the field the UI exposes: `bindable` rejects any non-scalar patch value with `EBADFIELD` (`links` excepted — it is stored as JSON), and the route answers 400 for that AND for the `SQLITE_CONSTRAINT` family, rather than handing better-sqlite3 a datatype throw and reporting 500 on plain bad input.