feat: auto-updater integration

- Install electron-updater
- New updater.ts: check/download/install with progress events
- IPC: updater:check, updater:download, updater:install, updater:status
- Preload bridge for updater API
- electron-builder publish config (github provider)
- Fix build files path: out -> electron-dist
- i18n keys for updater notifications (zh-CN + en)

electron/main/index.ts

@@ -3,6 +3,7 @@ import { app, BrowserWindow, nativeTheme, nativeImage } from 'electron'
 import { join } from 'path'
 import { restoreAndTrack } from './win-state'
 import { registerIpcHandlers } from './ipc-handlers'
+import { initUpdater } from './updater'
 
 let mainWindow: BrowserWindow | null = null
 
@@ -55,6 +56,7 @@ function createWindow(): void {
 app.whenReady().then(() => {
   registerIpcHandlers()
   createWindow()
+  initUpdater(mainWindow!)
 })
 
 app.on('window-all-closed', () => { app.quit() })