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.

client/src/hooks/__tests__/useSpin.test.ts

@@ -0,0 +1,57 @@
+/**
+ * @file useSpin.test.ts
+ * @description Tests the Refresh-button hook: the reload runs with no
+ * arguments, a click while it is in flight is dropped, and the spin lasts at
+ * least the floor even when the reload answers at once — also under StrictMode's
+ * mount → unmount → mount, which once left it spinning for good.
+ * @author Nguyễn Ngọc Trí Vĩ <vinnt@smartgift.vn>
+ */
+
+import { describe, it, expect, vi, afterEach } from "vitest";
+import { StrictMode } from "react";
+import { act, renderHook } from "@testing-library/react";
+import { useSpin } from "../useSpin";
+
+afterEach(() => vi.useRealTimers());
+
+describe("useSpin", () => {
+  it("drops a click while the reload is in flight, and spins for the floor after it answers", async () => {
+    vi.useFakeTimers();
+    let answer!: () => void;
+    const load = vi.fn(() => new Promise<void>((r) => (answer = r)));
+    const { result } = renderHook(() => useSpin(load, 600));
+
+    act(() => {
+      void result.current[1]();
+    });
+    expect(result.current[0]).toBe(true);
+    expect(load).toHaveBeenCalledWith();
+    act(() => {
+      void result.current[1]();
+    });
+    expect(load).toHaveBeenCalledTimes(1);
+
+    // Answered at once: still spinning until the floor, but a new click reloads.
+    await act(async () => answer());
+    expect(result.current[0]).toBe(true);
+    act(() => {
+      void result.current[1]();
+    });
+    expect(load).toHaveBeenCalledTimes(2);
+    await act(async () => {
+      answer();
+      await vi.advanceTimersByTimeAsync(600);
+    });
+    expect(result.current[0]).toBe(false);
+  });
+
+  it("stops spinning under StrictMode's double mount", async () => {
+    vi.useFakeTimers();
+    const { result } = renderHook(() => useSpin(() => undefined, 600), { wrapper: StrictMode });
+    await act(async () => {
+      void result.current[1]();
+      await vi.advanceTimersByTimeAsync(600);
+    });
+    expect(result.current[0]).toBe(false);
+  });
+});