feat: 增加媒体格式校验，支持 JPEG、PNG、GIF、MP4、WebM、WebP 格式

Sources/DuooomiBleSDK/Core/BleTypes.swift

@@ -35,6 +35,7 @@ public enum DuooomiBleError: LocalizedError {
     case transferFailed(String)
     case invalidFrame
     case permissionDenied
+    case unsupportedFormat(String)
 
     public var errorDescription: String? {
         switch self {
@@ -64,6 +65,8 @@ public enum DuooomiBleError: LocalizedError {
             return "Invalid protocol frame"
         case .permissionDenied:
             return "Bluetooth permission denied"
+        case .unsupportedFormat(let ext):
+            return "Unsupported file format: \(ext). Supported: jpeg, png, gif, mp4, webm, webp"
         }
     }
 }