feat: M1.1 完成 + M1.2 启动 — 全量更新

M1.1 收尾:
- 24项 P0/P1/P2 bug 修复 (Rust 107 tests + Flutter 15 tests)
- Flutter App v0.3: cupertino_icons 修复, 单元测试, 调试面板, APK 52.6MB
- 示例插件完善: manifest.json + 请求/响应示范 + 7个测试
- API 文档重写 (以 routes.rs 为唯一权威)
- MILESTONES.md 更新至 100%

M1.2 启动:
- P0: 插件管理 API 闭环 (handle_manager_message Custom 分支 + broadcast_plugin_states)
- ServiceManager 集成测试 8/8 (tests/m1_2_service_manager.rs)
- M1.2 测试计划 (docs/M1.2_TEST_PLAN.md, 18个E2E场景)
- 动态插件系统: auto_rollback + version_manager GC + 路径穿越防护

总计: Rust 115/115 测试, Flutter 15/15 测试, 零 warning

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

clients/flutter/lib/services/ble_service.dart

@@ -151,6 +151,29 @@ class BleService {
     }
   }
 
+  Future<void> sendCommand(String command) async {
+    final characteristic = _commandCharacteristic;
+    if (_connectedDevice == null) {
+      throw StateError('未连接 BLE 设备');
+    }
+    if (characteristic == null) {
+      throw StateError('未发现 BLE 命令特征值');
+    }
+
+    await characteristic.write(
+      utf8.encode(command),
+      withoutResponse: characteristic.properties.writeWithoutResponse,
+    );
+  }
+
+  Future<void> play() => sendCommand('play');
+
+  Future<void> pause() => sendCommand('pause');
+
+  Future<void> next() => sendCommand('next');
+
+  Future<void> previous() => sendCommand('prev');
+
   Future<void> disconnect() async {
     await _scanSubscription?.cancel();
     _scanSubscription = null;