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)

src/types/electron.d.ts

@@ -0,0 +1,26 @@
+/**
+ * Electron API Type Declarations
+ * Types for the APIs exposed via contextBridge
+ */
+
+export interface IpcRenderer {
+  invoke(channel: string, ...args: unknown[]): Promise<unknown>;
+  on(channel: string, callback: (...args: unknown[]) => void): (() => void) | void;
+  once(channel: string, callback: (...args: unknown[]) => void): void;
+  off(channel: string, callback?: (...args: unknown[]) => void): void;
+}
+
+export interface ElectronAPI {
+  ipcRenderer: IpcRenderer;
+  openExternal: (url: string) => Promise<void>;
+  platform: NodeJS.Platform;
+  isDev: boolean;
+}
+
+declare global {
+  interface Window {
+    electron: ElectronAPI;
+  }
+}
+
+export {};