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/components/conversation/ConversationView.tsx

@@ -59,6 +59,7 @@ import { api } from "../../lib/api";
 import { eventBus } from "../../lib/eventBus";
 import { isRemoteDataRefreshMessage } from "../../lib/remoteDataEvents";
 import { MessageList } from "./MessageList";
+import { useSpin } from "../../hooks/useSpin";
 import { useTranslation } from "react-i18next";
 import type { TranscriptMessage, TranscriptInfo, WSMessage } from "../../lib/types";
 
@@ -106,7 +107,6 @@ export function ConversationView({ sessionId, initialTranscriptId }: Conversatio
   const genRef = useRef(0);
   // Refresh-button spinner state - separate from initial `loading` so the
   // existing skeleton doesn't blink during a manual refresh.
-  const [refreshing, setRefreshing] = useState(false);
 
   // Load available transcript list (also rescanned on a short interval so
   // newly-spawned subagents appear in the dropdown without a page reload).
@@ -305,14 +305,7 @@ export function ConversationView({ sessionId, initialTranscriptId }: Conversatio
 
   // Manual refresh - surfaces a control in the toolbar so users can force
   // a sync without reloading the page.
-  const refresh = useCallback(async () => {
-    setRefreshing(true);
-    try {
-      await fetchNewMessages();
-    } finally {
-      setRefreshing(false);
-    }
-  }, [fetchNewMessages]);
+  const [refreshing, refresh] = useSpin(fetchNewMessages);
 
   // Scroll-up to load history
   const loadHistory = useCallback(async () => {