feat: US-001 — scaffold NeuralDesk Electron + React app

- electron-forge 7 + Vite plugin (vite-typescript template)
- React 19 + TypeScript 5 strict mode
- TanStack Router with file-based routing (4 routes: /, /timeline, /tasks, /projects)
- Tailwind CSS 3 + PostCSS with Figma design tokens (sidebar, primary, muted)
- Framer Motion, Lucide React, shadcn/ui utilities (cn, CVA, clsx, twMerge)
- AppShell layout: 240px sidebar with collapse toggle, active route highlighting
- Vite configs use .mts extension to avoid ESM/CJS conflict with electron-forge
- Full package build verified (linux x64)

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

src/main/index.ts

@@ -0,0 +1,63 @@
+import { app, BrowserWindow } from 'electron';
+import path from 'node:path';
+import started from 'electron-squirrel-startup';
+
+// Handle creating/removing shortcuts on Windows when installing/uninstalling.
+if (started) {
+  app.quit();
+}
+
+const createWindow = () => {
+  // Create the browser window.
+  const mainWindow = new BrowserWindow({
+    width: 1280,
+    height: 800,
+    minWidth: 900,
+    minHeight: 600,
+    titleBarStyle: 'hiddenInset',
+    webPreferences: {
+      preload: path.join(__dirname, 'preload.js'),
+      contextIsolation: true,
+      nodeIntegration: false,
+    },
+  });
+
+  // and load the index.html of the app.
+  if (MAIN_WINDOW_VITE_DEV_SERVER_URL) {
+    mainWindow.loadURL(MAIN_WINDOW_VITE_DEV_SERVER_URL);
+  } else {
+    mainWindow.loadFile(
+      path.join(__dirname, `../renderer/${MAIN_WINDOW_VITE_NAME}/index.html`),
+    );
+  }
+
+  // Open DevTools in development.
+  if (process.env.NODE_ENV === 'development') {
+    mainWindow.webContents.openDevTools();
+  }
+};
+
+// This method will be called when Electron has finished
+// initialization and is ready to create browser windows.
+// Some APIs can only be used after this event occurs.
+app.on('ready', createWindow);
+
+// Quit when all windows are closed, except on macOS. There, it's common
+// for applications and their menu bar to stay active until the user quits
+// explicitly with Cmd + Q.
+app.on('window-all-closed', () => {
+  if (process.platform !== 'darwin') {
+    app.quit();
+  }
+});
+
+app.on('activate', () => {
+  // On OS X it's common to re-create a window in the app when the
+  // dock icon is clicked and there are no other windows open.
+  if (BrowserWindow.getAllWindows().length === 0) {
+    createWindow();
+  }
+});
+
+// In this file you can include the rest of your app's specific main process
+// code. You can also put them in separate files and import them here.