feat: 重写 SDK 支持 iOS 12.2，移除 async/await 和 Combine

- 所有公开 API 改为 completion handler (Result<T, Error>)
- 状态通知改为 DuooomiBleSDKDelegate 协议
- 移除 Sendable、@MainActor、AsyncStream、CheckedContinuation
- 网络请求改为 URLSession.dataTask 回调
- BLE 通信改为 delegate + 闭包模式
- deployment target 降至 iOS 12.2

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

Sources/DuooomiBleSDK/Protocol/ProtocolConstants.swift

@@ -21,7 +21,7 @@ public enum FrameConstants {
     public static let screenSize = 360
 }
 
-public enum CommandType: UInt8, Sendable {
+public enum CommandType: UInt8 {
     case otaPackage = 0x02
     case transferBootAnimation = 0x03
     case transferAniVideo = 0x05