feat(desktop-client): add settings window and switch default API to production

- Open a dedicated settings BrowserWindow with general / login / diagnostics / about tabs
- Persist openAtLogin and keepRunningInBackground via desktop-settings.json; hide main window instead of quitting when background mode is on
- Default API base URL now points to api.shengxintui.com; LoginView and SettingsView share a single constant
- Restore wangyihao session cookies on probe and silent refresh, and accept the legacy http://mp.163.com console origin
- Drop the standalone diagnostics view in favor of the settings tab

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

apps/desktop-client/src/preload/bridge.ts

@@ -27,6 +27,11 @@ interface WindowModeRequest {
   animate?: boolean;
 }
 
+interface DesktopAppSettings {
+  openAtLogin: boolean;
+  keepRunningInBackground: boolean;
+}
+
 const rendererProxyRequestChannel = "desktop:renderer-devtools-proxy:request";
 const rendererProxyResponseChannel = "desktop:renderer-devtools-proxy:response";
 
@@ -120,6 +125,12 @@ const desktopBridge = {
       ipcRenderer.invoke("desktop:retry-publish-task", taskId) as Promise<CreatePublishJobResponse>,
     openExternalUrl: (url: string) =>
       ipcRenderer.invoke("desktop:open-external-url", url) as Promise<null>,
+    openSettingsWindow: () =>
+      ipcRenderer.invoke("desktop:open-settings-window") as Promise<null>,
+    getAppSettings: () =>
+      ipcRenderer.invoke("desktop:get-app-settings") as Promise<DesktopAppSettings>,
+    setAppSetting: (key: keyof DesktopAppSettings, value: boolean) =>
+      ipcRenderer.invoke("desktop:set-app-setting", key, value) as Promise<DesktopAppSettings>,
     syncRuntimeSession: (session: DesktopRuntimeSessionSyncRequest | null) =>
       ipcRenderer.invoke("desktop:runtime-session-sync", session) as Promise<null>,
     releaseRuntimeSession: (revoke?: boolean) =>