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/lanes/LaneChangesPanel.tsx

@@ -81,6 +81,7 @@ import { copyText } from "../../lib/clipboard";
 import { isSubmitEnter } from "../../lib/keys";
 import { toast } from "../../lib/toast";
 import { useArmed } from "../../hooks/useArmed";
+import { useSpin } from "../../hooks/useSpin";
 import { useUnsavedGuard } from "../../hooks/useUnsavedGuard";
 import {
   LaneDiffView,
@@ -1421,8 +1422,9 @@ export function LaneChangesPanel({
     setTreeChildren({});
     setExpandedDirs(new Set());
     setReread((n) => n + 1);
-    void load();
+    return load();
   };
+  const [rereading, runReread] = useSpin(rereadAll);
 
   const toggleCollapsed = (path: string) =>
     setCollapsed((prev) => {
@@ -1609,12 +1611,12 @@ export function LaneChangesPanel({
 
             <button
               type="button"
-              onClick={rereadAll}
+              onClick={runReread}
               aria-label={t("changes.refresh")}
               title={t("changes.refresh")}
               className="order-last ml-auto shrink-0 text-fg-muted hover:text-fg-primary"
             >
-              <RefreshCw className={`h-3.5 w-3.5 ${loading ? "animate-spin" : ""}`} />
+              <RefreshCw className={`h-3.5 w-3.5 ${loading || rereading ? "animate-spin" : ""}`} />
             </button>
           </div>