feat(settings): support gateway source switching

tests/test_workers.py

@@ -423,13 +423,16 @@ class WorkerTests(unittest.TestCase):
         ) as analyze, mock.patch("app.gui.workers.ai.gen_title") as gen_title:
             result = worker.execute()
 
-        analyze.assert_called_once_with(
-            "补充要求",
-            "输出语言：繁体中文",
-            ["first.jpg", "second.jpg"],
-            config={"ai": {"backend": "cmhub"}},
-            cmhub_config_path="cmhub.json",
+        analyze.assert_called_once()
+        args, kwargs = analyze.call_args
+        self.assertEqual(
+            ("补充要求", "输出语言：繁体中文", ["first.jpg", "second.jpg"]),
+            args,
         )
+        self.assertEqual(worker.config, kwargs["config"])
+        self.assertEqual("cmhub.json", kwargs["cmhub_config_path"])
+        self.assertIn("cmhub_api_key", worker.config["_cmshopee_ai_runtime"])
+        self.assertNotIn("direct_models", worker.config["_cmshopee_ai_runtime"])
         gen_title.assert_not_called()
         self.assertEqual(expected, result)