feat(electron): scaffold electron-vite project structure

Initialize Wave 1 Electron integration with:
- electron v40.6.1, electron-vite v5.0.0, electron-builder v26.8.1
- Main entry point: electron/main/index.ts with app:// protocol registration
- Preload placeholder: electron/preload/index.ts for Wave 2 IPC
- electron.vite.config.ts with unified renderer chunk splitting strategy
- tsconfig.electron.json with ESNext module support
- Updated package.json with electron dependencies and scripts:
  - electron:dev, electron:build, electron:preview
- All original scripts (dev, build, test, etc) remain unchanged
- TypeScript compilation verified: tsc --noEmit passes
- Ready for Wave 2: IPC bridge and contextBridge exposure

dashboard/electron/main/index.ts

@@ -0,0 +1,98 @@
+import { app, BrowserWindow, protocol } from 'electron'
+import path from 'path'
+import { fileURLToPath } from 'url'
+
+const __filename = fileURLToPath(import.meta.url)
+const __dirname = path.dirname(__filename)
+
+let mainWindow: BrowserWindow | null = null
+
+/**
+ * Register app:// custom protocol BEFORE app.whenReady()
+ * This is critical for electron-vite to work correctly
+ */
+function registerAppProtocol() {
+  protocol.registerSchemesAsPrivileged([
+    {
+      scheme: 'app',
+      privileges: {
+        secure: true,
+        standard: true,
+        allowServiceWorkers: true,
+      },
+    },
+  ])
+}
+
+/**
+ * Create the main application window
+ */
+function createWindow() {
+  mainWindow = new BrowserWindow({
+    width: 1200,
+    height: 800,
+    minWidth: 800,
+    minHeight: 600,
+    webPreferences: {
+      preload: path.join(__dirname, '../preload/index.js'),
+      nodeIntegration: false,
+      contextIsolation: true,
+    },
+  })
+
+  // Load the app using app:// protocol
+  // electron-vite will handle serving the renderer from app://host/index.html
+  if (process.env.VITE_DEV_SERVER_URL) {
+    // Development: load from electron-vite dev server
+    mainWindow.loadURL(process.env.VITE_DEV_SERVER_URL)
+  } else {
+    // Production: load from bundled renderer
+    mainWindow.loadURL('app://host/index.html')
+  }
+
+  mainWindow.on('closed', () => {
+    mainWindow = null
+  })
+}
+
+/**
+ * Register app:// protocol handler (for production)
+ */
+function registerAppProtocolHandler() {
+  protocol.handle('app', (request) => {
+    const filePath = new URL(request.url).pathname
+    return new Response(
+      `Cannot handle app:// requests. Renderer should be served by electron-vite.`
+    )
+  })
+}
+
+/**
+ * App event: when app is ready
+ */
+app.on('ready', () => {
+  registerAppProtocolHandler()
+  createWindow()
+})
+
+/**
+ * App event: when all windows are closed (non-macOS behavior)
+ */
+app.on('window-all-closed', () => {
+  // On macOS, applications typically stay open until the user quits
+  if (process.platform !== 'darwin') {
+    app.quit()
+  }
+})
+
+/**
+ * App event: when app is activated (macOS)
+ */
+app.on('activate', () => {
+  if (mainWindow === null) {
+    createWindow()
+  }
+})
+
+// Register protocol BEFORE app.whenReady()
+registerAppProtocol()