Add Codex restart hint after provider switch

tests/hooks/useProviderActions.test.tsx

@@ -192,6 +192,10 @@ describe("useProviderActions", () => {
     expect(switchProviderMutateAsync).toHaveBeenCalledWith(provider.id);
     expect(settingsApiGetMock).not.toHaveBeenCalled();
     expect(settingsApiApplyMock).not.toHaveBeenCalled();
+    expect(toastSuccessMock).toHaveBeenCalledWith(
+      "切换成功，请重启客户端以生效",
+      { closeButton: true },
+    );
   });
 
   it("warns but still switches providers that require proxy when proxy is not running", async () => {