feat(xai): add Grok account management UI with four-locale strings

Add XaiOAuthSection (device-code login, account list, default selection)
backed by the generalized useManagedAuth hook, wire it into the Auth
Center and both Claude provider forms, and expose model fetching for
signed-in accounts.

- Accounts requiring re-auth stay visible in the account selector as
  disabled items with an expired badge instead of silently vanishing.
- Auth status refetches periodically so a revoked refresh token surfaces
  without reloading the panel.
- All strings ship in zh/en/ja/zh-TW; a locale coverage test pins every
  required key in all four locales.

src/components/providers/forms/ProviderForm.tsx

@@ -107,6 +107,7 @@ import {
   useHermesFormState,
   useCopilotAuth,
   useCodexOauth,
+  useXaiOauth,
 } from "./hooks";
 import { ConfirmDialog } from "@/components/ConfirmDialog";
 import { useSettingsQuery } from "@/lib/query";
@@ -514,10 +515,19 @@ function ProviderFormFull({
   );
 
   // Copilot OAuth 认证状态（仅 Claude 应用需要）
-  const { isAuthenticated: isCopilotAuthenticated } = useCopilotAuth();
+  const { isAuthenticated: isCopilotAuthenticated, accounts: copilotAccounts } =
+    useCopilotAuth();
 
   // Codex OAuth 认证状态（ChatGPT Plus/Pro 反代）
-  const { isAuthenticated: isCodexOauthAuthenticated } = useCodexOauth();
+  const {
+    isAuthenticated: isCodexOauthAuthenticated,
+    accounts: codexOauthAccounts,
+  } = useCodexOauth();
+
+  const {
+    isAuthenticated: isXaiOauthAuthenticated,
+    accounts: xaiOauthAccounts,
+  } = useXaiOauth();
 
   // 选中的 GitHub 账号 ID（多账号支持）
   const [selectedGitHubAccountId, setSelectedGitHubAccountId] = useState<
@@ -528,6 +538,9 @@ function ProviderFormFull({
   const [selectedCodexAccountId, setSelectedCodexAccountId] = useState<
     string | null
   >(() => resolveManagedAccountId(initialData?.meta, "codex_oauth"));
+  const [selectedXaiAccountId, setSelectedXaiAccountId] = useState<
+    string | null
+  >(() => resolveManagedAccountId(initialData?.meta, "xai_oauth"));
   const [codexFastMode, setCodexFastMode] = useState<boolean>(
     () => initialData?.meta?.codexFastMode ?? false,
   );
@@ -1146,6 +1159,9 @@ function ProviderFormFull({
     const isCodexOauthProvider =
       templatePreset?.providerType === "codex_oauth" ||
       initialData?.meta?.providerType === "codex_oauth";
+    const isXaiOauthProvider =
+      templatePreset?.providerType === "xai_oauth" ||
+      initialData?.meta?.providerType === "xai_oauth";
     if (isCopilotProvider && !isCopilotAuthenticated) {
       toast.error(
         t("copilot.loginRequired", {
@@ -1162,6 +1178,56 @@ function ProviderFormFull({
       );
       return;
     }
+    if (isXaiOauthProvider && !isXaiOauthAuthenticated) {
+      toast.error(
+        t("xaiOauth.loginRequired", {
+          defaultValue: "请先登录 xAI 账号",
+        }),
+      );
+      return;
+    }
+
+    const selectedAccountIsUsable = (
+      accountId: string | null,
+      accounts: Array<{ id: string; requires_reauth: boolean }>,
+    ) =>
+      accountId === null ||
+      accounts.some(
+        (account) => account.id === accountId && !account.requires_reauth,
+      );
+    if (
+      isCopilotProvider &&
+      !selectedAccountIsUsable(selectedGitHubAccountId, copilotAccounts)
+    ) {
+      toast.error(
+        t("managedAuth.selectedAccountUnavailable", {
+          defaultValue: "已绑定账号不存在，请重新选择账号",
+        }),
+      );
+      return;
+    }
+    if (
+      isCodexOauthProvider &&
+      !selectedAccountIsUsable(selectedCodexAccountId, codexOauthAccounts)
+    ) {
+      toast.error(
+        t("managedAuth.selectedAccountUnavailable", {
+          defaultValue: "已绑定账号不存在，请重新选择账号",
+        }),
+      );
+      return;
+    }
+    if (
+      isXaiOauthProvider &&
+      !selectedAccountIsUsable(selectedXaiAccountId, xaiOauthAccounts)
+    ) {
+      toast.error(
+        t("managedAuth.selectedAccountNeedsReauth", {
+          defaultValue: "已绑定 xAI 账号不存在或需要重新登录",
+        }),
+      );
+      return;
+    }
 
     // OMO Other Fields JSON：B 类（格式错了保存下去数据就坏了）
     if (
@@ -1198,14 +1264,19 @@ function ProviderFormFull({
     // cloud_provider（如 Bedrock）通过模板变量处理认证，跳过通用校验
     if (category !== "official" && category !== "cloud_provider") {
       if (appId === "claude") {
-        if (!isCodexOauthProvider && !baseUrl.trim()) {
+        if (!isCodexOauthProvider && !isXaiOauthProvider && !baseUrl.trim()) {
           issues.push(
             t("providerForm.endpointRequired", {
               defaultValue: "非官方供应商请填写 API 端点",
             }),
           );
         }
-        if (!isCopilotProvider && !isCodexOauthProvider && !apiKey.trim()) {
+        if (
+          !isCopilotProvider &&
+          !isCodexOauthProvider &&
+          !isXaiOauthProvider &&
+          !apiKey.trim()
+        ) {
           issues.push(
             t("providerForm.apiKeyRequired", {
               defaultValue: "非官方供应商请填写 API Key",
@@ -1278,6 +1349,9 @@ function ProviderFormFull({
     const isCodexOauthProvider =
       templatePreset?.providerType === "codex_oauth" ||
       initialData?.meta?.providerType === "codex_oauth";
+    const isXaiOauthProvider =
+      templatePreset?.providerType === "xai_oauth" ||
+      initialData?.meta?.providerType === "xai_oauth";
 
     let settingsConfig: string;
 
@@ -1483,7 +1557,13 @@ function ProviderFormFull({
               authProvider: "codex_oauth",
               accountId: selectedCodexAccountId ?? undefined,
             }
-          : undefined,
+          : isXaiOauthProvider
+            ? {
+                source: "managed_account",
+                authProvider: "xai_oauth",
+                accountId: selectedXaiAccountId ?? undefined,
+              }
+            : undefined,
       // GitHub Copilot 多账号：保存关联的账号 ID
       githubAccountId:
         isCopilotProvider && selectedGitHubAccountId
@@ -1519,7 +1599,9 @@ function ProviderFormFull({
           : undefined,
       apiFormat:
         appId === "claude" && category !== "official"
-          ? localApiFormat
+          ? isXaiOauthProvider
+            ? "openai_responses"
+            : localApiFormat
           : appId === "codex" && category !== "official"
             ? localCodexApiFormat
             : undefined,
@@ -1552,7 +1634,10 @@ function ProviderFormFull({
           ? Number(localCodexMaxOutputTokens)
           : undefined,
       isFullUrl:
-        supportsFullUrl && category !== "official" && localIsFullUrl
+        supportsFullUrl &&
+        category !== "official" &&
+        !isXaiOauthProvider &&
+        localIsFullUrl
           ? true
           : undefined,
     };
@@ -2109,13 +2194,19 @@ function ProviderFormFull({
                 templatePreset?.providerType === "codex_oauth" ||
                 initialData?.meta?.providerType === "codex_oauth"
               }
+              isXaiOauthPreset={
+                templatePreset?.providerType === "xai_oauth" ||
+                initialData?.meta?.providerType === "xai_oauth"
+              }
               usesOAuth={
                 templatePreset?.requiresOAuth === true ||
                 templatePreset?.providerType === "github_copilot" ||
                 initialData?.meta?.providerType === "github_copilot" ||
                 baseUrl.includes("githubcopilot.com") ||
                 templatePreset?.providerType === "codex_oauth" ||
-                initialData?.meta?.providerType === "codex_oauth"
+                initialData?.meta?.providerType === "codex_oauth" ||
+                templatePreset?.providerType === "xai_oauth" ||
+                initialData?.meta?.providerType === "xai_oauth"
               }
               isCopilotAuthenticated={isCopilotAuthenticated}
               selectedGitHubAccountId={selectedGitHubAccountId}
@@ -2125,6 +2216,9 @@ function ProviderFormFull({
               onCodexAccountSelect={setSelectedCodexAccountId}
               codexFastMode={codexFastMode}
               onCodexFastModeChange={setCodexFastMode}
+              isXaiOauthAuthenticated={isXaiOauthAuthenticated}
+              selectedXaiAccountId={selectedXaiAccountId}
+              onXaiAccountSelect={setSelectedXaiAccountId}
               templateValueEntries={templateValueEntries}
               templateValues={templateValues}
               templatePresetName={templatePreset?.name || ""}