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/pages/__tests__/Workspace.test.tsx

@@ -758,6 +758,21 @@ describe("split panes", () => {
     expect(screen.getByTestId("run-param").textContent).toBe("agenthub-lane-1-1");
   });
 
+  it("a pane's X stops just its session, without taking it out of the tab first", async () => {
+    withRuns([live(0), live(1), live(2)]);
+    await open("/workspace?lane=1&run=agenthub-lane-1");
+    await ctrlClick(screen.getByTestId("console-tab-1"));
+    await ctrlClick(screen.getByTestId("console-tab-2"));
+
+    withRuns([live(0), live(2)]);
+    await userEvent.setup().click(screen.getByTestId("pane-stop-1"));
+    await settle();
+    expect(api.run.kill).toHaveBeenCalledTimes(1);
+    expect(api.run.kill).toHaveBeenCalledWith("agenthub-lane-1-1");
+    expect(shownPanes()).toEqual(["pane-0", "pane-2"]);
+    expect(screen.queryByTestId("console-tab-1")).toBeNull();
+  });
+
   it("drops a remembered pane whose session is gone", async () => {
     window.localStorage.setItem(
       "agenthub.workspace.paneLayout",