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)

resources/icons/.gitkeep

@@ -0,0 +1,6 @@
+# Placeholder for icon files
+# Add the following icons:
+# - icon.icns (macOS)
+# - icon.ico (Windows)
+# - icon.png (Linux)
+# - tray-icon.png (System tray)