refactor(desktop): 替换 WebUI 为 Electron + electron-vite 桌面壳方案

- 使用 electron-vite 构建 main/preload，electron-builder 打包分发
- main process: dev 模式直连 localhost:3000，生产模式 spawn sidecar binary
- 添加 loading 页面，server 就绪前显示加载动画
- 更新 catalog 依赖: electron, electron-vite, electron-builder
- 移除 @webui-dev/bun-webui 依赖

AGENTS.md

@@ -11,7 +11,7 @@ Guidelines for AI agents working in this Bun monorepo.
 - **Package Manager**: Bun — **NOT npm / yarn / pnpm**
 - **Apps**:
   - `apps/server` - TanStack Start fullstack web app (see `apps/server/AGENTS.md`)
-  - `apps/desktop` - Electrobun desktop shell, loads server in native window (see `apps/desktop/AGENTS.md`)
+  - `apps/desktop` - Electron desktop shell, sidecar server pattern (see `apps/desktop/AGENTS.md`)
 - **Packages**: `packages/utils`, `packages/tsconfig` (shared configs)
 
 ## Build / Lint / Test Commands
@@ -41,9 +41,11 @@ bun db:studio             # Open Drizzle Studio
 
 ### Desktop App (`apps/desktop`)
 ```bash
-bun dev                   # Start Electrobun dev mode (requires server dev running)
-bun build                 # Build canary release
-bun build:stable          # Build stable release
+bun dev                   # electron-vite dev mode (requires server dev running)
+bun build                 # electron-vite build (main + preload)
+bun build:win             # Build + package for Windows
+bun build:mac             # Build + package for macOS
+bun build:linux           # Build + package for Linux
 bun fix                   # Biome auto-fix
 bun typecheck             # TypeScript check
 ```
@@ -158,11 +160,14 @@ export const myTable = pgTable('my_table', {
 │   │   │       ├── api/  # ORPC contracts, routers, middlewares
 │   │   │       └── db/   # Drizzle schema
 │   │   └── AGENTS.md
-│   └── desktop/          # Electrobun desktop shell
+│   └── desktop/          # Electron desktop shell
 │       ├── src/
-│       │   └── bun/
-│       │       └── index.ts       # Main process entry
-│       ├── electrobun.config.ts   # Electrobun configuration
+│       │   ├── main/
+│       │   │   └── index.ts       # Main process entry
+│       │   └── preload/
+│       │       └── index.ts       # Preload script
+│       ├── electron.vite.config.ts
+│       ├── electron-builder.yml   # Packaging config
 │       └── AGENTS.md
 ├── packages/
 │   ├── tsconfig/         # Shared TS configs
@@ -175,4 +180,4 @@ export const myTable = pgTable('my_table', {
 ## See Also
 
 - `apps/server/AGENTS.md` - Detailed TanStack Start / ORPC patterns
-- `apps/desktop/AGENTS.md` - Electrobun desktop development guide
+- `apps/desktop/AGENTS.md` - Electron desktop development guide