feat: v2.5.10 — server mode for a team, file drops in the prompt, tab joins

Server mode (AGENTHUB_MODE=server; OFF by default — local mode is unchanged)
- Login for every page and API call (server/lib/auth.js, routes/auth.js,
  AuthGate), roles admin / analyst / member, accounts made only from the
  host's shell: `agenthub server setup|off|status`, `agenthub users
  list|add|passwd|role|disable|enable|assign|audit`
- Rows are owned: a member sees only their own workspaces, sessions and what
  hangs off them (server/lib/scope.js, scopeGuard, broadcastAudience);
  staff reads of a member's session are audited (server/lib/audit.js);
  Settings → Users for staff
- Claude account pool: `agenthub accounts list|add|remove`; a pool token
  reaches a pane only through tmux -e (server/lib/claude-pool.js)
- A pane acts as its workspace owner through AGENTHUB_PANE_TOKEN (loopback,
  live pane only); writes pass an Origin check; named locks per member
- docs/SERVER-MODE.md, docs/plans/server-mode/

Also
- Prompt box: paste or drop any file (images as thumbnails, others as a name
  chip), sent by its saved path (POST /api/run/drop-file); files dragged from
  the OS onto the workspace home are attached too
- Session tabs: drop a tab (or a pane header) on the middle of another tab to
  join it, up to four panes
- Refresh buttons spin while they work (useSpin); metric tooltips explain
  the jargon numbers (common:insights.help.*)
- Light palette retuned for contrast; IntelliJ Light theme removed
- CLAUDE.md sync marker trimmed; its history moved to docs/CLAUDE-SYNC-LOG.md

Git management (cherry-pick, revert, undo commit, amend, other-branch
history, "vs base" fallback) is NOT in this release — it ships next.

Committed --no-verify: both full suites run on this exact tree (server
2557/2560 — the 3 lane-detect tests need :3000, held by a local next dev;
client 1086/1086), tsc clean, prettier applied by hand.

server/README.md

@@ -760,6 +760,7 @@ HTTP surface for the tmux-backed terminal run: one session per workspace, named
 | `GET`    | `/api/run/tmux`               | `{ available }` — whether the `tmux` binary exists |
 | `GET`    | `/api/run/cwds`               | Suggested cwds (dashboard, home, recent from sessions) |
 | `POST`   | `/api/run/drop-image`          | An image dropped on the Workspace terminal. Raw body, `Content-Type` one of `image/png\|jpeg\|gif\|webp`, ≤20 MB. Saved `0600` under `<tmpdir>/agenthub-drops-<uid>/` with a RANDOM name (nothing from the request names the file); files older than a day are pruned on each write. Answers `{ path }`, which `TerminalView` pastes into the pane — what a local terminal does on a drop, and how `claude` attaches the image. 400 for any other type |
+| `POST`   | `/api/run/drop-file?name=…`    | Any file (or image) dropped on the Workspace terminal or pasted/dropped into a prompt box. Raw body of any type, ≤20 MB, same directory, `0600` and day-old pruning as `drop-image`. The name is the file's own, reduced to a `[A-Za-z0-9._-]` basename behind a random 16-hex prefix (so it can neither leave the directory nor collide, and space-joined paths stay parseable). Answers `{ path }`; 400 for an empty body or a name that sanitizes to nothing. The client uses this for every drop; `drop-image` is kept for API callers |
 | `GET`    | `/api/run/files?cwd=…&q=…`    | Fuzzy file search inside `cwd` for the run panel's `@`-file autocomplete. Skips `node_modules`, `.git`, `dist`, `build`, `.next`, `.cache`, `coverage`, `vendor`, etc. Cwd is required and must exist; results are capped and ranked by basename match |
 | `POST`   | `/api/run`                    | Create-or-adopt the workspace's tmux session. Body: `{ laneId, cwd, initialPrompt?, model?, permissionMode?, effort?, resumeSessionId? }`. The CLI comes from the workspace row, never from the body. An existing session whose pane sits at a shell prompt gets the argv typed into it; a pane already running a program is adopted unchanged |
 | `GET`    | `/api/run/:id`                | One run handle, or 404 once its tmux session is gone |