feat(demo): SDK 暴露 rawJsonEvents 调试通道；Demo 日志显示 BLE 收发原始 JSON

- BleTypes.kt 新增 BleRawJsonEvent（TX/RX，含 cmd 名/十六进制类型/JSON 字符串），KDoc 标注调试用、非业务契约
- BleProtocolService.sendJSON 内 emit TX；新增 rawJsonEmitter 注入回调避免协议层反向依赖
- DuooomiBleSDK 公开 SharedFlow<BleRawJsonEvent>；handleIncomingMessage 入口尽力 UTF-8 解码 emit RX（非 JSON 字节流静默跳过）
- DemoScreen LaunchedEffect 订阅，前缀 → TX / ← RX 写入现有 logs 列表
- iOS 当前无对应通道，本通道为 Android Demo 调试增强

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

sdk/src/main/kotlin/com/duooomi/ble/DuooomiBleSDK.kt

@@ -54,6 +54,13 @@ class DuooomiBleSDK(context: Context, val config: DuooomiBleConfig) {
     private val _error = MutableStateFlow<String?>(null)
     val error: StateFlow<String?> = _error.asStateFlow()
 
+    /**
+     * BLE JSON 协议层原始收发事件流。**调试用**——日志/抓包/UI 联调展示，
+     * 不属业务行为契约（iOS 版无对应通道）。集成方不要依赖它做业务逻辑。
+     */
+    private val _rawJsonEvents = MutableSharedFlow<BleRawJsonEvent>(extraBufferCapacity = 32)
+    val rawJsonEvents: SharedFlow<BleRawJsonEvent> = _rawJsonEvents.asSharedFlow()
+
     // MARK: - Internal Services
 
     private val bleClient = BleClient(context)
@@ -85,6 +92,7 @@ class DuooomiBleSDK(context: Context, val config: DuooomiBleConfig) {
     init {
         BleLog.i("SDK initialized (apiHost=${config.apiHost}, brand=${config.brand})", "SDK")
         setupDisconnectHandler()
+        protocolService.rawJsonEmitter = { evt -> _rawJsonEvents.tryEmit(evt) }
         // 启动时把持久化记录回放到 StateFlow
         _upgradeRecords.value = upgradeRecordStore.all
         upgradeRecordStore.onChange = { records ->
@@ -702,6 +710,7 @@ class DuooomiBleSDK(context: Context, val config: DuooomiBleConfig) {
 
     private fun handleIncomingMessage(commandType: Byte, data: ByteArray) {
         val typeValue = commandType.toInt() and 0xFF
+        emitRawJsonRx(typeValue, data)
         val opId = "$typeValue"
 
         // Check for prepareTransfer with key-based opId
@@ -746,6 +755,26 @@ class DuooomiBleSDK(context: Context, val config: DuooomiBleConfig) {
         throw DuooomiBleError.BrandMismatch(expected = expected, actual = actual)
     }
 
+    private fun emitRawJsonRx(typeValue: Int, data: ByteArray) {
+        runCatching {
+            val cleaned = data.filter { it != 0.toByte() }.toByteArray()
+            if (cleaned.isEmpty()) return@runCatching
+            val jsonStr = String(cleaned, Charsets.UTF_8)
+            if (jsonStr.startsWith("{") || jsonStr.startsWith("[")) {
+                val name = CommandType.fromValue(typeValue)?.name
+                    ?: "UNKNOWN(0x%02X)".format(typeValue)
+                _rawJsonEvents.tryEmit(
+                    BleRawJsonEvent(
+                        direction = BleRawJsonEvent.Direction.RX,
+                        commandType = typeValue,
+                        commandName = name,
+                        json = jsonStr
+                    )
+                )
+            }
+        }
+    }
+
     private fun parseJsonResponse(data: ByteArray): JSONObject {
         // Device responses may contain null bytes
         val cleaned = data.filter { it != 0.toByte() }.toByteArray()