chore(scripts): 开发脚本支持 Flutter Windows 桌面端

- pnpm start:dev 默认在 Windows 上启动桌面端（非 Web）
- 新增 pnpm start:dev:app:win 强制 Windows 桌面
- 新增 pnpm start:dev:app:web 强制 Chrome Web
- SIGINT 清理时同时终止 nuanji_app.exe
- 汇总输出区分桌面/Web 模式

package.json

@@ -7,6 +7,8 @@
     "start:dev:backend": "node scripts/dev.mjs backend",
     "start:dev:admin": "node scripts/dev.mjs admin",
     "start:dev:app": "node scripts/dev.mjs app",
+    "start:dev:app:win": "node scripts/dev.mjs app:win",
+    "start:dev:app:web": "node scripts/dev.mjs app:web",
     "start:stop": "node scripts/stop.mjs"
   },
   "devDependencies": {