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/Workspace.tsx

@@ -67,7 +67,7 @@ import { api } from "../lib/api";
 import type { CwdSuggestion, RunHandle, RunListResponse } from "../lib/api";
 import type { Lane, LaneFeature, ProofFeature, Session } from "../lib/types";
 import { toast } from "../lib/toast";
-import { confirmDiscard } from "../lib/confirm";
+import { confirmDialog, confirmDiscard } from "../lib/confirm";
 import { keepIfSame } from "../lib/keepIfSame";
 import { useLanes } from "../hooks/useLanes";
 import { LaneConsolePane } from "../components/run/LaneConsolePane";
@@ -347,6 +347,29 @@ function ConsoleArea({
     else onNewSession?.();
   };
 
+  // A pane header's X: stops that one session, as a one-pane tab's X does —
+  // an AI session may be mid-turn, so it asks first; a shell holds no agent.
+  const stopPane = async (slot: number) => {
+    const run = runOf(slot);
+    if (!run) return;
+    if (
+      run.tool !== "shell" &&
+      !(await confirmDialog({
+        title: t("tabs.stopTitle", { name: label(run) }),
+        message: t("tabs.stopBody"),
+        confirmLabel: t("tabs.stopConfirm"),
+        destructive: true,
+      }))
+    )
+      return;
+    try {
+      await api.run.kill(run.id);
+      ended(slot);
+    } catch (err) {
+      toast.error(err);
+    }
+  };
+
   // A split menu's "New terminal" or AI tool (bare, as the tab bar's `+`
   // starts it) in the first free slot, placed on that side of the pane —
   // unless the workspace changed while it started.
@@ -466,6 +489,7 @@ function ConsoleArea({
         toolLabel={aiTools.label}
         onNewSplit={(target, edge, tool) => void newSplit(target, edge, tool)}
         stateOf={stateOf}
+        onStop={(slot) => void stopPane(slot)}
         renderPane={(slot) => (
           <LaneConsolePane
             lanes={lanes}