feat(codex): decouple upstream format selector from model-mapping toggle

The Codex provider form tied Chat-format conversion and route takeover (model
mapping) to one toggle, so a provider serving a native Responses API could not
use model mapping without forcing Chat Completions conversion.

- Promote the upstream format (Chat Completions / Responses) to an independent,
  always-visible selector that triggers no sub-menus on its own.
- The local-routing toggle now solely gates the advanced sub-sections: model
  mapping catalog, plus reasoning capability when the format is Chat.
- Persist modelCatalog / codexChatReasoning based on the takeover toggle and
  derive its initial state from saved catalog presence (no new persisted field).
- Refresh codexConfig i18n (zh/en/ja/zh-TW): add upstreamFormat* keys and reword
  the routing/advanced hints to reflect the decoupling.
- Fix codexChatProviderPresets test expectation for the Doubao Seed 2.1 Pro rename.

src/components/providers/forms/ProviderForm.tsx

@@ -150,6 +150,16 @@ const codexApiFormatFromWireApi = (
   }
 };
 
+// 从已保存的 settingsConfig 推断 Codex 模型映射条目数（用于决定本地路由初始开关）。
+const codexCatalogCountFromSettings = (settingsConfig: unknown): number => {
+  if (settingsConfig && typeof settingsConfig === "object") {
+    const models = (settingsConfig as { modelCatalog?: { models?: unknown } })
+      .modelCatalog?.models;
+    return Array.isArray(models) ? models.length : 0;
+  }
+  return 0;
+};
+
 export const normalizeCodexCatalogModelsForSave = (
   models: CodexCatalogModel[],
 ): CodexCatalogModel[] => {
@@ -568,24 +578,29 @@ function ProviderFormFull({
     resetCodexConfig,
   } = useCodexConfigState({ initialData });
 
+  const initialCodexApiFormat: CodexApiFormat =
+    initialData?.meta?.apiFormat === "openai_chat"
+      ? "openai_chat"
+      : initialData?.meta?.apiFormat === "openai_responses"
+        ? "openai_responses"
+        : (codexApiFormatFromWireApi(
+            extractCodexWireApi(
+              typeof initialData?.settingsConfig?.config === "string"
+                ? initialData.settingsConfig.config
+                : "",
+            ),
+          ) ?? "openai_responses");
+
   const [localCodexApiFormat, setLocalCodexApiFormat] =
-    useState<CodexApiFormat>(() => {
-      if (initialData?.meta?.apiFormat === "openai_chat") {
-        return "openai_chat";
-      }
-      if (initialData?.meta?.apiFormat === "openai_responses") {
-        return "openai_responses";
-      }
-      return (
-        codexApiFormatFromWireApi(
-          extractCodexWireApi(
-            typeof initialData?.settingsConfig?.config === "string"
-              ? initialData.settingsConfig.config
-              : "",
-          ),
-        ) ?? "openai_responses"
-      );
-    });
+    useState<CodexApiFormat>(initialCodexApiFormat);
+
+  // 本地路由（接管）开关 —— 纯模型映射门控，与上游格式完全独立。
+  // 没有独立持久化字段，初值仅按「是否已配置模型映射」推断（有 catalog 即视为
+  // 接管已开）。只在 useState 初始化与预设重置点设置，跟 localCodexApiFormat
+  // 对称，避免漂移。
+  const [codexTakeoverEnabled, setCodexTakeoverEnabled] = useState<boolean>(
+    () => codexCatalogCountFromSettings(initialData?.settingsConfig) > 0,
+  );
 
   const { configError: codexConfigError, debouncedValidate } =
     useCodexTomlValidation();
@@ -616,6 +631,7 @@ function ProviderFormFull({
       const template = getCodexCustomTemplate();
       resetCodexConfig(template.auth, template.config);
       setCodexChatReasoning({});
+      setCodexTakeoverEnabled(false);
     }
   }, [appId, initialData, selectedPresetId, resetCodexConfig]);
 
@@ -1262,7 +1278,7 @@ function ProviderFormFull({
             ? setCodexWireApi(codexConfig ?? "", "responses")
             : (codexConfig ?? "");
         const normalizedCatalogModels =
-          category !== "official" && localCodexApiFormat === "openai_chat"
+          category !== "official" && codexTakeoverEnabled
             ? normalizeCodexCatalogModelsForSave(codexCatalogModels)
             : [];
         // Sync first catalog row's model into config.toml so Codex uses it as default
@@ -1458,6 +1474,7 @@ function ProviderFormFull({
       codexChatReasoning:
         appId === "codex" &&
         category !== "official" &&
+        codexTakeoverEnabled &&
         localCodexApiFormat === "openai_chat"
           ? normalizeCodexChatReasoningForSave(codexChatReasoning)
           : undefined,
@@ -1610,6 +1627,8 @@ function ProviderFormFull({
           codexApiFormatFromWireApi(extractCodexWireApi(template.config)) ??
             "openai_responses",
         );
+        // 自定义模板无模型映射，路由默认关闭
+        setCodexTakeoverEnabled(false);
       }
       if (appId === "gemini") {
         resetGeminiConfig({}, {});
@@ -1652,6 +1671,8 @@ function ProviderFormFull({
           codexApiFormatFromWireApi(extractCodexWireApi(config)) ??
           "openai_responses",
       );
+      // 路由开关与格式无关，仅按预设是否带模型映射决定
+      setCodexTakeoverEnabled((preset.modelCatalog?.length ?? 0) > 0);
 
       form.reset({
         name: preset.nameKey ? t(preset.nameKey) : preset.name,
@@ -2124,6 +2145,8 @@ function ProviderFormFull({
               }
               autoSelect={endpointAutoSelect}
               onAutoSelectChange={setEndpointAutoSelect}
+              takeoverEnabled={codexTakeoverEnabled}
+              onTakeoverEnabledChange={setCodexTakeoverEnabled}
               apiFormat={localCodexApiFormat}
               onApiFormatChange={handleCodexApiFormatChange}
               codexChatReasoning={codexChatReasoning}