feat: v2.7.7 — File Explorer on workspaces and the user's home, clone with per-user git identity

- File Explorer (Files in the sidebar, /files; also from a workspace's Files
  tab, portalled so no panel clips it), laid out like GNOME Files: places
  (Home, workspaces, Trash), Back/Forward/Up, path bar, search, icon grid with
  image thumbnails or list, labelled New/Upload, selection action bar, hidden
  files behind Ctrl+H, right-click menus and the usual keys.
  Make, rename, move, copy (within a workspace, between workspaces, home ↔
  workspace), delete into a per-account trash restorable for 7 days, streamed
  upload of files and whole folders (≤ 500 MB a batch, Replace / Keep both /
  Skip on a taken name), download a file or a zip of anything.
  server/lib/file-explorer.js, /api/lanes/:id/fs/*, /api/homes/:who/fs/*.
- The user's home: every dot entry at its top stays hidden and refused
  (also via a symlink, download, zip or as a copy source); an admin may view
  other users' homes read-only, audited.
- write-as learns move/copy (re-run `sudo agenthub server install-system`).
- Hardening: a write to a workspace re-checks its owner by the live role;
  S3 keeps its server.conf if the file stops reading and a tmux call never
  falls back to the host's server; the AI Proxy gateway marks what it relays
  and the dashboard refuses it; a NUL in a pane's argv/env is refused.
- OpenAPI for the new routes (server/openapi-extra/files.js); docs (API,
  SERVER-MODE, CLAUDE.md) updated.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

docs/API.md

@@ -258,6 +258,61 @@ folder name inside an existing folder, `400 EBADNAME`/`ENOTFOUND`,
 not at all without one (`403 EFOLDER`); a member's folder is made as the
 member (S3).
 
+#### File Explorer
+
+```
+GET  /api/lanes/:id/fs/list?path=          { path, parent, entries: [{ name, path, type: dir|file|link|linkdir|other, size, mtime }], truncated }
+POST /api/lanes/:id/fs/mkdir               { path }                                   → 201 { path }
+POST /api/lanes/:id/fs/newfile             { path }                                   → 201 { path }  (empty file)
+POST /api/lanes/:id/fs/rename              { path, name }                             → { path }
+POST /api/lanes/:id/fs/move                { paths, dest, conflict? }                 → { moved }
+POST /api/lanes/:id/fs/copy                { paths, dest, conflict?, fromLane? }      → { copied }
+POST /api/lanes/:id/fs/delete              { paths }                                  → { trashed: [ids] }
+GET  /api/lanes/:id/fs/trash                                                          → { items: [{ id, name, laneId, path, isDir, deletedAt }], keepDays }
+POST /api/lanes/:id/fs/trash/restore       { id }                                     → { path, laneId }
+POST /api/lanes/:id/fs/trash/purge         { id | "all" }                             → { purged }
+POST /api/lanes/:id/fs/upload?path=&conflict=   raw body, streamed                    → 201 { path } | 200 { skipped: true }
+GET  /api/lanes/:id/fs/zip?p=<path>&p=…    application/zip, streamed
+```
+
+The workspace **File Explorer** — the **Files** page in the sidebar (`/files?lane=<id>&path=<folder>`), laid out like GNOME Files (workspaces as places, Back/Forward, a path bar, icon grid or list, hidden files behind Ctrl+H), and the same manager in a dialog from a workspace's Files tab (the folder button; "Open in File Explorer" on a folder). `?session=` / `?source=` pick the same folder the
+git reads do. Paths go through the read path's guards (`lanePath`, the parent
+`resolveInLane`-confined, the last segment kept as a name so a symlink is acted
+on as a link); nothing in `.git`, no secret file, never the workspace folder
+itself (`400 EBADPATH` / `403 ESECRET`). Writes are same-origin and run as the
+folder's account (a member's through `write-as`). `conflict` = `fail`
+(default: `409 EEXISTS` with `error.names`), `skip`, `keep` (a free
+"name (1).ext") or `replace` (the old one goes to the trash first). Delete
+moves into the account's trash — a member's `~/.local/share/agenthub/trash/`,
+the host's `<data dir>/trash/<user id>/` — restorable for 7 days. A copy may
+come `fromLane` another workspace the caller can see, of the same account
+(`403 EFOREIGN` otherwise). An upload is at most 500 MB (`413 ETOOBIG`, from
+`Content-Length` before a byte is stored), a zip at most 2 GB / 50,000 files.
+Under S3 a move/copy/delete needs the installed `write-as` to know
+`move`/`copy`: `409 EUPGRADE` until `sudo agenthub server install-system` is
+re-run.
+
+#### File Explorer on a home
+
+```
+GET  /api/homes                                   { homes: [{ id: "me" | <username>, label, readOnly }] }
+GET  /api/homes/:who/fs/list|trash|zip|download   as the workspace routes above
+POST /api/homes/:who/fs/mkdir|newfile|rename|move|copy|delete|upload|trash/restore|trash/purge
+```
+
+The same File Explorer on a user's HOME (`server/lib/homes.js`): under S3 their
+own Linux home, in server mode without S3 their folder under
+`AGENTHUB_USERS_ROOT`, in local mode (or for an admin with no Linux account)
+the host account's home. Every dot entry at the TOP of a home (`.ssh`,
+`.claude`, `.config`, `.agenthub`, `.bashrc`…) is hidden from listings and
+refused for every read and write — also through a symlink, a download or a
+zip (`403 ESECRET`); dot files deeper down are ordinary. `:who` is `me`; an
+admin may also name another user — read-only (`403 EREADONLY` on every
+write), each read written to the audit log. A copy goes home ↔ workspace
+(`fromHome` on the workspace route, `fromLane` on the home one) when both are
+one Linux account; each side is checked under its own rule. A home is never a
+workspace. The **Files** page opens on `?home=me` by default.
+
 #### Clone a repository into a new workspace
 
 ```