feat(settings): support gateway source switching

app/gui/main_window.py

@@ -109,6 +109,9 @@ class MainWindow(QMainWindow):
         self.tabs.currentChanged.connect(self._on_tab_changed)
         for title in TAB_TITLES:
             self.tabs.addTab(self._build_tab(title), title)
+        settings_tab = self._settings_tab()
+        if hasattr(settings_tab, "settingsSaved"):
+            settings_tab.settingsSaved.connect(self._on_settings_saved)
         self.setCentralWidget(self.tabs)
         self.show_status("就绪", level="muted")
         if startup_status:
@@ -182,6 +185,14 @@ class MainWindow(QMainWindow):
             if hasattr(widget, "refresh_tasks"):
                 widget.refresh_tasks()
 
+    def _on_settings_saved(self, backend):
+        for index in range(self.tabs.count()):
+            widget = self.tabs.widget(index)
+            if hasattr(widget, "refresh_gateway_state"):
+                widget.refresh_gateway_state()
+        label = "自定义网关" if str(backend) == "direct" else "默认网关"
+        self.show_status("设置已保存，当前使用%s" % label, level="success")
+
     def _on_tab_changed(self, index):
         if self._reverting_tab_change:
             self._last_tab_index = index