refactor(desktop): 从 Tauri 迁移到 Electrobun

- 移除 Tauri v2 代码 (src-tauri/, copy.ts)
- 添加 Electrobun 配置和入口 (electrobun.config.ts, src/bun/index.ts)
- 更新 package.json 使用 catalog 管理 electrobun 依赖
- 移除 server 中的 @tauri-apps/api 依赖
- 更新 AGENTS.md 文档

apps/server/package.json

@@ -27,7 +27,6 @@
     "@tanstack/react-router": "catalog:",
     "@tanstack/react-router-ssr-query": "catalog:",
     "@tanstack/react-start": "catalog:",
-    "@tauri-apps/api": "catalog:",
     "drizzle-orm": "catalog:",
     "drizzle-zod": "catalog:",
     "postgres": "catalog:",