feat(core): initialize project skeleton with Electron + React + TypeScript

Set up the complete project foundation for ClawX, a graphical AI assistant:

- Electron main process with IPC handlers, menu, tray, and gateway management
- React renderer with routing, layout components, and page scaffolding
- Zustand state management for gateway, settings, channels, skills, chat, and cron
- shadcn/ui components with Tailwind CSS and CSS variable theming
- Build tooling with Vite, electron-builder, and TypeScript configuration
- Testing setup with Vitest and Playwright
- Development configurations (ESLint, Prettier, gitignore, env example)

vitest.config.ts

@@ -0,0 +1,23 @@
+import { defineConfig } from 'vitest/config';
+import react from '@vitejs/plugin-react';
+import { resolve } from 'path';
+
+export default defineConfig({
+  plugins: [react()],
+  test: {
+    globals: true,
+    environment: 'jsdom',
+    setupFiles: ['./tests/setup.ts'],
+    include: ['tests/**/*.{test,spec}.{ts,tsx}'],
+    coverage: {
+      reporter: ['text', 'json', 'html'],
+      exclude: ['node_modules/', 'tests/'],
+    },
+  },
+  resolve: {
+    alias: {
+      '@': resolve(__dirname, 'src'),
+      '@electron': resolve(__dirname, 'electron'),
+    },
+  },
+});