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/lib/read-pool.js

@@ -17,7 +17,14 @@ const JOBS = {
   workflows: (conn, a) =>
     require("./workflow-stats").computeWorkflowData(
       conn,
-      { status: a.status || null, tool: a.tool || null, range: a.range || null },
+      {
+        status: a.status || null,
+        tool: a.tool || null,
+        range: a.range || null,
+        // A server-mode member's user id: part of the args, so the in-flight
+        // share never hands one member another's numbers.
+        member: a.member ?? null,
+      },
       a.sections || null
     ),
   // Not a read: the worker runs it on its own writable connection (below), so
@@ -102,7 +109,7 @@ function dispatch(job, args) {
  * Run a named read job off the event loop. Concurrent calls with the same job
  * and args share one run; with `maxAgeMs`, a result that young is reused too,
  * so N open dashboards cost one query per window instead of N. Args are part
- * of the key, so a result is only reused for the very same query.
+ * of the key, so a member's scoped result is never handed to anyone else.
  *
  * @param {keyof JOBS} job
  * @param {object} [args] structured-cloneable