feat: Electron desktop app — hardening, IPC bridge, and dev launch fixes

- Dev/prod URL auto-detection (Vite 5173 in dev, server 3000 in prod)
- Typed IPC bridge via preload (notifications, badge, window controls, updates, deep links)
- Native OS notifications via NotificationController with window focus suppression
- Auto-update via electron-updater with UpdateToast UI
- Deep linking (backspace:// protocol) for macOS and Windows/Linux
- Window state persistence (position, size, maximize across restarts)
- Tray icon with graceful fallback when icon asset missing
- Suppress PWA service worker polling/reloads inside Electron
- Platform detection layer (isElectron, getElectronAPI)
- Root workspace scripts (dev:desktop, build:desktop)
- Document BACKSPACE_URL and BACKSPACE_UPDATE_URL env vars

packages/desktop/src/preload.ts

@@ -1,13 +1,10 @@
 import { contextBridge, ipcRenderer } from 'electron';
 
 contextBridge.exposeInMainWorld('backspace', {
+  // Platform info
   platform: process.platform,
-  showNotification: (title: string, body: string) => {
-    ipcRenderer.send('show-notification', { title, body });
-  },
-  setBadgeCount: (count: number) => {
-    ipcRenderer.send('set-badge-count', count);
-  },
+
+  // Window controls
   minimize: () => {
     ipcRenderer.send('minimize-window');
   },
@@ -17,4 +14,39 @@ contextBridge.exposeInMainWorld('backspace', {
   close: () => {
     ipcRenderer.send('close-window');
   },
+
+  // Notifications & badge
+  showNotification: (title: string, body: string) => {
+    ipcRenderer.send('show-notification', { title, body });
+  },
+  setBadgeCount: (count: number) => {
+    ipcRenderer.send('set-badge-count', count);
+  },
+
+  // Auto-update
+  onUpdateAvailable: (callback: (info: { version: string }) => void) => {
+    ipcRenderer.on('update-available', (_event, info) => callback(info));
+  },
+  onUpdateDownloaded: (callback: (info: { version: string }) => void) => {
+    ipcRenderer.on('update-downloaded', (_event, info) => callback(info));
+  },
+  onUpdateError: (callback: (error: string) => void) => {
+    ipcRenderer.on('update-error', (_event, error) => callback(error));
+  },
+  installUpdate: () => {
+    ipcRenderer.send('install-update');
+  },
+  checkForUpdates: () => {
+    ipcRenderer.send('check-for-updates');
+  },
+
+  // Window focus
+  onWindowFocusChange: (callback: (focused: boolean) => void) => {
+    ipcRenderer.on('window-focus-changed', (_event, focused) => callback(focused));
+  },
+
+  // Deep linking
+  onDeepLink: (callback: (url: string) => void) => {
+    ipcRenderer.on('deep-link', (_event, url) => callback(url));
+  },
 });