feat: add Grok official subscription quota query

Add SuperGrok subscription usage display, following the existing
Claude Code / Codex official-subscription pattern (protocol ported
from steipete/CodexBar):

- New subscription_grok service: reads Grok CLI credentials from
  ~/.grok/auth.json, calls the grok.com GrokBuildBilling gRPC-web
  endpoint, and parses the response via heuristic protobuf scanning
  (used percent, reset time, zero-usage special case)
- Transient failures (network errors, HTTP 408, gRPC deadline/
  cancelled) propagate as Err so the frontend retries and keeps the
  last good value; auth failures map to Expired with a re-login hint
- Tier naming by reset distance: weekly limit, monthly, or a new
  "credits" tier (i18n added for zh/en/ja/zh-TW; tray shows "c")
- New get_xai_oauth_quota command: xai_oauth providers (managed
  SuperGrok OAuth accounts) query the same billing endpoint with
  their bound account token; ProviderCard auto-renders the quota
  footer for them and hides the usage-script entry, and the tray /
  usage-script path routes xai_oauth providers to the managed
  account instead of the host app's CLI credentials
- UsageScriptModal: drop the config-content heuristic for official
  detection; category === "official" is the single source of truth

Claude-Session: https://claude.ai/code/session_01LSNvhEfuoJHaQLZcYQgBU5

src/components/UsageScriptModal.tsx

@@ -160,7 +160,7 @@ function detectBalanceProvider(baseUrl: string | undefined): boolean {
 }
 
 function isOfficialSubscriptionProvider(provider: Provider, appId: AppId) {
-  if (!["claude", "codex", "gemini"].includes(appId)) return false;
+  if (!["claude", "codex", "gemini", "grokbuild"].includes(appId)) return false;
   if (provider.category === "official") return true;
 
   const config = provider.settingsConfig as Record<string, any>;
@@ -188,6 +188,12 @@ function isOfficialSubscriptionProvider(provider: Provider, appId: AppId) {
       (!baseUrl || (typeof baseUrl === "string" && baseUrl.trim() === ""))
     );
   }
+  // grokbuild 不做配置启发式，只认上方的 category === "official"：官方态判定
+  // 在后端是 TOML 解析（grok_config::is_official_live_config），正则无法忠实
+  // 镜像（引号键/inline table/非法 TOML 均会误判为官方），误判会让本组件的
+  // state 初始化丢弃已保存的非官方脚本。claude/codex/gemini 的启发式建立在
+  // 已解析的 JSON 字段上是精确的，不受此限。官方判定以 category 为 SSOT 的
+  // 理由见 ProviderCard 中的注释。
   return false;
 }