feat: 终端同步加固与移动端最小验证 App

- 服务端: RTTY_TOKEN 最小鉴权; Ready.resumed 会话恢复语义; 会话按 ID 原子创建
- 服务端: 桌面端连接/重连时全屏 ANSI 重绘; 惰性语义快照(仅移动端订阅时生成); Ping/Pong 心跳
- 桌面端: 输入改二进制帧无损透传; 指数退避自动重连; token 输入框; resumed 状态展示
- 移动端: 修复 client=mobile 参数(此前永远收不到快照); 新增最小验证 App(连接/快照显示/输入/Keybar); 支持 token; Android 网络权限
- 测试: 修正 e2e onReady 签名; 新增移动端 widget 测试

mobile/README.md

@@ -0,0 +1,17 @@
+# rtty_mobile
+
+A new Flutter project.
+
+## Getting Started
+
+This project is a starting point for a Flutter application.
+
+A few resources to get you started if this is your first Flutter project:
+
+- [Learn Flutter](https://docs.flutter.dev/get-started/learn-flutter)
+- [Write your first Flutter app](https://docs.flutter.dev/get-started/codelab)
+- [Flutter learning resources](https://docs.flutter.dev/reference/learning-resources)
+
+For help getting started with Flutter development, view the
+[online documentation](https://docs.flutter.dev/), which offers tutorials,
+samples, guidance on mobile development, and a full API reference.