feat(server): 添加游戏服务器框架 | add game server framework (#366)

**@esengine/server** - 游戏服务器框架 | Game server framework
- 文件路由系统 | File-based routing
- Room 生命周期 (onCreate, onJoin, onLeave, onTick, onDispose)
- @onMessage 装饰器 | Message handler decorator
- 玩家管理与断线处理 | Player management with auto-disconnect
- 内置 JoinRoom/LeaveRoom API | Built-in room APIs
- defineApi/defineMsg 类型安全辅助函数 | Type-safe helpers

**create-esengine-server** - CLI 脚手架工具 | CLI scaffolding
- 生成 shared/server/client 项目结构 | Project structure
- 类型安全的协议定义 | Type-safe protocol definitions
- 包含 GameRoom 示例 | Example implementation

**其他 | Other**
- 删除旧的 network-server 包 | Remove old network-server
- 更新服务器文档 | Update server documentation

packages/framework/server/tsup.config.ts

@@ -0,0 +1,11 @@
+import { defineConfig } from 'tsup'
+
+export default defineConfig({
+    entry: ['src/index.ts'],
+    format: ['esm'],
+    dts: true,
+    clean: true,
+    sourcemap: true,
+    external: ['ws', '@esengine/rpc'],
+    treeshake: true,
+})