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.

server/__tests__/systemd-service.test.js

@@ -76,6 +76,15 @@ describe("systemd-service — unit content", linuxOnly, () => {
     assert.doesNotMatch(body, /^Restart=on-failure$/m);
   });
 
+  it("stops only the server process, so an update never takes the lane panes with it", () => {
+    // tmux forks its server from whichever process first asks for a session —
+    // the dashboard, after a boot with autostart on — and that server sits in
+    // this unit's cgroup. The default KillMode=control-group would kill it,
+    // and every running agent, on each update's restart.
+    svc.writeUserService(UNIT);
+    assert.match(unitFile(), /^KillMode=process$/m);
+  });
+
   it("carries the ownership marker, so a hand-written unit is never clobbered", () => {
     svc.writeUserService(UNIT);
     assert.match(unitFile(), /agenthub-managed-unit/);