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/web/tsconfig.json

@@ -20,6 +20,6 @@
       "@/*": ["./src/*"]
     }
   },
-  "include": ["src/**/*", "node_modules/vite-plugin-pwa/client.d.ts"],
+  "include": ["src/**/*", "src/platform/electron.d.ts", "node_modules/vite-plugin-pwa/client.d.ts"],
   "exclude": ["src/**/*.test.ts", "src/**/*.test.tsx"]
 }