feat(desktop): 顶栏积分余额芯片 + 提交遇余额不足透出友好文案（P3 租户感知）

让计费对终端用户可见（守 desktop/admin 边界：只读自己租户，不碰 admin 配置）：
- TopBar 加积分余额芯片（Coins 图标）：常态显余额；硬拦截开+余额≤0 → 红「余额不足」；
  偏低 → 橙。tooltip 显租户名 + 是否拦截。api.tenantCurrent() 读 /tenants/current。
- App 登录后拉租户上下文，每 20s 轮询 + 运行结束即刷新（余额跟手）。
- submitTask 遇 402 解析后端 error 文案透出（如「租户积分余额不足，请充值后再试」），
  在运行面板报错处显示，用户知道为何被拦。

live 验证(preview)：芯片显示 公司A 余额 15.9 ✓；enforce 开+余额0 时 /tenants/current
标 enforce+余额0（芯片转「余额不足」）、提交 402 带友好文案 ✓；tsc + 48 测试全过。

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

sundynix-desktop/frontend/src/App.tsx

@@ -14,7 +14,7 @@ import { Placeholder } from "./views/Placeholder";
 import { CommandPalette, type Command } from "./components/CommandPalette";
 import { UpdateBanner } from "./components/UpdateBanner";
 import { Login } from "./views/Login";
-import { submitTask, streamTokens, streamExec, taskStatus, listRuns, authMe, logout, type Identity, type AuthUser } from "./lib/api";
+import { submitTask, streamTokens, streamExec, taskStatus, listRuns, authMe, logout, tenantCurrent, type Identity, type AuthUser, type TenantCtx } from "./lib/api";
 import type { TaskDsl } from "./lib/dsl";
 import { emptyRun, type RunState } from "./lib/run";
 import { ToastProvider } from "./ui";
@@ -41,6 +41,7 @@ const PLACEHOLDERS: Partial<Record<ViewKey, { title: string; desc: string }>> =
 export default function App() {
   const [view, setView] = useState<ViewKey>("home");
   const [user, setUser] = useState<AuthUser | null>(null);
+  const [tenant, setTenant] = useState<TenantCtx | null>(null);
   const [authLoading, setAuthLoading] = useState(true);
   const identity = useMemo<Identity>(() => ({ userId: user?.id ?? "", sessionId: getSessionId() }), [user]);
   const [run, setRun] = useState<RunState>(emptyRun);
@@ -82,8 +83,29 @@ export default function App() {
   const onLogout = useCallback(() => {
     logout();
     setUser(null);
+    setTenant(null);
   }, []);
 
+  // 租户上下文 + 积分余额：登录后拉取，并每 20s 轮询保持大致实时（顶栏余额芯片用）。
+  const refreshTenant = useCallback(() => {
+    tenantCurrent()
+      .then(setTenant)
+      .catch(() => {});
+  }, []);
+  useEffect(() => {
+    if (!user) {
+      setTenant(null);
+      return;
+    }
+    refreshTenant();
+    const t = window.setInterval(refreshTenant, 20000);
+    return () => window.clearInterval(t);
+  }, [user, refreshTenant]);
+  // 运行结束余额会被扣，立即刷新一次（比等轮询更跟手）。
+  useEffect(() => {
+    if (run.phase === "done") refreshTenant();
+  }, [run.phase, refreshTenant]);
+
   const commands = useMemo<Command[]>(() => {
     const go = (key: ViewKey) => () => setView(key);
     return [
@@ -216,7 +238,7 @@ export default function App() {
         style={{ background: "radial-gradient(60% 100% at 50% 0%, rgba(124,92,246,0.10), transparent 70%)" }}
       />
       <UpdateBanner />
-      <TopBar user={user} onLogout={onLogout} onCommand={() => setCmdOpen(true)} />
+      <TopBar user={user} tenant={tenant} onLogout={onLogout} onCommand={() => setCmdOpen(true)} />
       <ApprovalBar run={run} />
       <div className="relative flex min-h-0 flex-1">
         <LeftNav active={view} onSelect={setView} />