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/routes/users.js

@@ -0,0 +1,73 @@
+/**
+ * @file users.js
+ * @description `/api/users` — server mode's per-user view for an admin or
+ * analyst (members are refused by STAFF_ONLY_PREFIXES in server/lib/auth.js):
+ * `GET /` lists every account with its workspaces, sessions and $ spent in the
+ * last 7 and 30 days (from `token_usage_hourly`, sessions owned through their
+ * workspace — server/lib/scope.js); `GET /audit` the newest audit entries
+ * (server/lib/audit.js). Read-only: accounts are managed from the host's shell.
+ * @author Nguyễn Ngọc Trí Vĩ <vinnt@smartgift.vn>
+ */
+
+const { Router } = require("express");
+const { db, stmts } = require("../db");
+const { listUsers } = require("../lib/auth");
+const { sessionWhere } = require("../lib/scope");
+const { listAudit } = require("../lib/audit");
+
+const router = Router();
+
+const USAGE_COLS = [
+  "input_tokens",
+  "output_tokens",
+  "cache_read_tokens",
+  "cache_write_tokens",
+  "cache_write_1h_tokens",
+  "web_search_requests",
+  "web_fetch_requests",
+  "code_execution_requests",
+];
+
+/** $ and tokens a member's sessions spent since `sinceHour` (UTC `YYYY-MM-DDTHH`). */
+function usageSince(userId, sinceHour, rules) {
+  const { calculateCost } = require("./pricing");
+  const w = sessionWhere({ user: { id: userId, role: "member" } }, "s.id", "s.lane_id");
+  const rows = db
+    .prepare(
+      `SELECT h.model, h.speed, h.inference_geo, h.service_tier,
+              ${USAGE_COLS.map((c) => `SUM(h.${c}) AS ${c}`).join(", ")}
+         FROM token_usage_hourly h JOIN sessions s ON s.id = h.session_id
+        WHERE h.hour >= ? AND ${w.where}
+        GROUP BY h.model, h.speed, h.inference_geo, h.service_tier`
+    )
+    .all(sinceHour, ...w.params);
+  const tokens = rows.reduce(
+    (n, r) => n + r.input_tokens + r.output_tokens + r.cache_read_tokens + r.cache_write_tokens,
+    0
+  );
+  return { cost: rows.length ? calculateCost(rows, rules).total_cost : 0, tokens };
+}
+
+const hourAgo = (days) => new Date(Date.now() - days * 864e5).toISOString().slice(0, 13);
+
+router.get("/", (_req, res) => {
+  const rules = stmts.listPricing.all();
+  const users = listUsers().map((u) => {
+    const w = sessionWhere({ user: { id: u.id, role: "member" } });
+    return {
+      ...u,
+      workspaces: db.prepare("SELECT COUNT(*) AS n FROM lanes WHERE owner_id = ?").get(u.id).n,
+      sessions: db.prepare(`SELECT COUNT(*) AS n FROM sessions WHERE ${w.where}`).get(...w.params)
+        .n,
+      last7d: usageSince(u.id, hourAgo(7), rules),
+      last30d: usageSince(u.id, hourAgo(30), rules),
+    };
+  });
+  res.json({ users });
+});
+
+router.get("/audit", (req, res) => {
+  res.json({ entries: listAudit(req.query.limit) });
+});
+
+module.exports = router;