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.

README.md

@@ -61,8 +61,10 @@ Internal build — all rights reserved.
   other its conversation with a prompt box — sending a message resumes it,
   opening never does; **Analyst** in the right panel opens its analysis). A workspace opens on its home: a
   prompt box that starts a new session, Recents, and the workspace's own
-  Instructions, Memory, Context files and extra Folders, which Claude and Codex
-  sessions start with.
+  Instructions, Memory, Context files (picked with + or dragged in from the OS)
+  and extra Folders, which Claude and Codex sessions start with. Files and
+  images dragged onto a terminal or a prompt box are uploaded and attached by
+  their saved path.
 - **Settings as one page per section** (`/settings/<section>`): a left nav
   grouped General (General / Data / About / Appearance / Pet / Notifications) /
   Agents / Routing / Cost / Git, a search box (Ctrl+F) over every section whose
@@ -78,7 +80,7 @@ Internal build — all rights reserved.
   (marketplaces → every plugin → AgentHub last → one session reload).
 - **Appearance.** Settings → Appearance picks Dark / Light / System (follows the
   OS live) and a theme per mode — dark: Default, Darcula, Apple Dark, Orca Dark;
-  light: Default, Apple Light, IntelliJ Light, Canvas, Orca Light. Each mode
+  light: Default, Apple Light, Canvas, Orca Light. Each mode
   remembers its own theme, so the sidebar's quick toggle swaps between the two.
   Per-browser only.
 - **Notification sounds.** Settings → Notifications picks a sound (None, Chime,
@@ -92,6 +94,10 @@ Internal build — all rights reserved.
   (`agenthub statusline install`, [docs/STATUSLINE.md](docs/STATUSLINE.md)), and
   Prometheus rules + Grafana boards for `/api/metrics`
   (`docker-compose.monitoring.yml`, [docs/MONITORING.md](docs/MONITORING.md)).
+- **Server mode for a shared dashboard** (`agenthub server setup`): a login on
+  every page and API call, with admin / member / analyst roles. It is off by
+  default, and a local install does not change. It is login only, without
+  per-user isolation yet ([docs/SERVER-MODE.md](docs/SERVER-MODE.md)).
 
 ## Prerequisites