feat: 6채널 미만 수신 시 자동 retry (패킷 드랍 대응)

onMultiChannelComplete에서 receivedCount < 6이면:
- 자동 retry (collector reset + 재전송)
- 최대 2회 재시도 (maxMeasureRetries)
- INCOMPLETE_SCAN 로그 기록
- 6채널 온전히 수신된 경우만 BV 파이프라인 진행

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

app/src/main/java/com/example/medilightv2android/ui/views/monitoring/PiezoMonitoringView.kt

@@ -107,6 +107,17 @@ fun PiezoMonitoringView(appState: AppState) {
 
         bleManager.piezoCollector.onMultiChannelComplete = { channels ->
             handler.post {
+                // 6채널 미만 수신 → 자동 retry (패킷 드랍 대응)
+                val receivedCount = channels.count { it.buffer.isNotEmpty() }
+                if (receivedCount < 6 && measureRetryCount < maxMeasureRetries) {
+                    measureRetryCount++
+                    Log.w("PiezoMonitor", "Incomplete: $receivedCount/6 channels — retry $measureRetryCount")
+                    bleManager.debugLogger.warn("INCOMPLETE_SCAN $receivedCount/6 — retry $measureRetryCount")
+                    bleManager.piezoCollector.reset()
+                    bleManager.sendChannelsOnly()
+                    return@post
+                }
+
                 lastMultiChannelResult.clear()
                 lastMultiChannelResult.addAll(channels)