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.

docs/CLI.md

@@ -101,6 +101,10 @@ The CLI talks to the local dashboard server — **API-backed commands require it
 | `agenthub status` | At-a-glance up/down indicator (`●` running / `○` not running); exits `1` when down |
 | `agenthub start [--port N]` | Start the production server **in the background** (detached; survives closing the terminal), wait up to 30 s for `/api/health`, print the URL + PID and the `kill <pid>` stop command. Logs append to `data/agenthub-server.log`. No-ops with a pointer when a server is already up. Requires a built client (`npm run build` once) |
 | `agenthub repl` (aliases `shell`, `i`) | Open the **interactive shell** — see [Interactive REPL](#interactive-repl) |
+| `agenthub server setup [--hostname name] [--admin name]` | Turn **server mode** on (logins for a shared dashboard): writes `AGENTHUB_MODE=server` (and `DASHBOARD_ALLOWED_HOSTS`) to the settings file and creates the first admin, asking for its password. Works with the server down; restart it afterwards. See [SERVER-MODE.md](SERVER-MODE.md) |
+| `agenthub server off` / `agenthub server status` | Back to local mode (accounts kept) / show the mode and account count |
+| `agenthub accounts list\|add <name>\|remove <name>` | The **Claude account pool**: new Claude sessions spread over these accounts (each a `claude setup-token` token, typed hidden or read from stdin). `list` shows live panes, $ in the last 5 h / 7 d, and quota. See [SERVER-MODE.md](SERVER-MODE.md#claude-account-pool) |
+| `agenthub users list\|add <name> [--role admin\|analyst\|member]\|passwd <name>\|role <name> <role>\|disable <name>\|enable <name>\|assign <workspace id> <name>\|audit [--limit N]` | Server mode's accounts, written straight to the database; `assign` gives a workspace made before server mode an owner; `audit` lists admin/analyst reads of members' sessions. Inside a dashboard pane in server mode, every command acts as the workspace's owner through the pane's `AGENTHUB_PANE_TOKEN`. A password is typed hidden twice, or read from the first line of stdin |
 
 ### Interactive REPL