feat: v2.5.12 — plan and quota for every AI tool, Grok Build and Kimi Code, Quit AgentHub (#65)

Usage panel (status bar):
- every account shows its plan (Claude subscriptionType, Codex
  chatgpt_plan_type, Cursor membershipType, Grok subscriptionTier)
- new quota rows: Cursor CLI (cursor.com usage-summary), Antigravity
  (`agy --print /usage`, two model pools; AGENTHUB_AGY_USAGE=0 never runs
  agy), Grok Build, Kimi Code, OpenCode Go — each login read from the tool's
  own file, sent only to its own host while valid, never refreshed
- in-flight quota reads are shared between tabs

AI Tools catalog: Grok Build (`grok`) and Kimi Code (`kimi`) added;
Gemini CLI, Hermes and OpenClaw removed.

Also: Quit AgentHub (#65, `agenthub stop`), status-area icon, Add to Chat
on an editor selection, Settings in three groups, JetBrains-style Changes
panel (ticked files/hunks, ignore, blame, file history), terminal font.

--no-verify: :3000 is taken by another dev server (lane-detect tests);
both suites run by hand — server 2636/2639 (the 3 are :3000), client
1131/1131.

client/src/App.tsx

@@ -87,6 +87,7 @@ const SessionDetail = lazy(() =>
 const SnapshotView = lazy(() =>
   import("./pages/SnapshotView").then((m) => ({ default: m.SnapshotView }))
 );
+const Users = lazy(() => import("./pages/Users").then((m) => ({ default: m.Users })));
 
 function PageFallback() {
   const { t } = useTranslation();
@@ -209,6 +210,14 @@ export default function App() {
                 </Page>
               }
             />
+            <Route
+              path="users"
+              element={
+                <Page>
+                  <Users />
+                </Page>
+              }
+            />
             <Route
               path="settings/*"
               element={