feat(phase1): architecture skeleton

- Electron 33 main process with frameless window, IPC, win-state persistence
- Preload with contextBridge typed API (window, theme, dialog)
- Vue 3 + Pinia + Element Plus + Vue Router renderer
- Dark/light dual theme via CSS custom properties
- TitleBar with window controls + theme toggle
- StatusBar placeholder
- Design spec document

src/main/index.ts

@@ -0,0 +1,51 @@
+// src/main/index.ts
+import { app, BrowserWindow, nativeTheme } from 'electron'
+import { join } from 'path'
+import { restoreAndTrack } from './win-state'
+import { registerIpcHandlers } from './ipc-handlers'
+
+let mainWindow: BrowserWindow | null = null
+
+function createWindow(): void {
+  mainWindow = new BrowserWindow({
+    width: 1200,
+    height: 800,
+    minWidth: 900,
+    minHeight: 600,
+    title: 'JRedisDesktop',
+    backgroundColor: nativeTheme.shouldUseDarkColors ? '#0f0f1a' : '#f8fafc',
+    webPreferences: {
+      preload: join(__dirname, '../preload/index.js'),
+      contextIsolation: true,
+      nodeIntegration: false,
+      sandbox: false,
+    },
+    frame: false,
+    titleBarStyle: 'hidden',
+  })
+
+  restoreAndTrack(mainWindow)
+
+  if (process.env.ELECTRON_RENDERER_URL) {
+    mainWindow.loadURL(process.env.ELECTRON_RENDERER_URL)
+  } else {
+    mainWindow.loadFile(join(__dirname, '../renderer/index.html'))
+  }
+
+  mainWindow.on('closed', () => { mainWindow = null })
+
+  nativeTheme.on('updated', () => {
+    mainWindow?.webContents.send('theme:os-updated', nativeTheme.shouldUseDarkColors)
+  })
+}
+
+app.whenReady().then(() => {
+  registerIpcHandlers()
+  createWindow()
+})
+
+app.on('window-all-closed', () => { app.quit() })
+
+app.on('activate', () => {
+  if (BrowserWindow.getAllWindows().length === 0) createWindow()
+})