fix: Placement 그래프를 선택된 Method 결과로 통일

- 그래프 벽 표시: analyzer.analyzeChannel(B 고정) → lastWallResults(선택 Method)
- lastWallResults state 추가: 콜백에서 allWalls 저장 → 그래프에서 참조
- Method C 선택 시에도 V41Detector의 ant/post가 그래프에 정확히 표시
- dot 색상 + 그래프 벽 + depth mm 모두 동일 Method 결과 사용

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

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

@@ -68,6 +68,7 @@ fun PlacementGuideView(appState: AppState) {
     var scanCount by remember { mutableIntStateOf(0) }
     var isLocked by remember { mutableStateOf(false) }
     var lastChannelData by remember { mutableStateOf<List<PiezoChannelData>>(emptyList()) }
+    var lastWallResults by remember { mutableStateOf<List<Pair<Int, Int>?>>(List(6) { null }) }
     var debounceCount by remember { mutableIntStateOf(0) }
     var lastGuidePhase by remember { mutableStateOf(PlacementPhase.VERTICAL) }
     var lastHintChangeMs by remember { mutableStateOf(0L) }
@@ -374,11 +375,20 @@ fun PlacementGuideView(appState: AppState) {
                         verticalArrangement = Arrangement.spacedBy(6.dp)
                     ) {
                         Text("Echo Waveforms", fontSize = 13.sp, fontWeight = FontWeight.Bold, color = MlPrimary)
+                        val graphMethod = com.example.medilightv2android.managers.GreenZoneConstants.detectionMethod
+                        val graphAnalyzerA = com.example.medilightv2android.managers.PiezoEchoAnalyzerA.shared
                         for (ch in 0 until 6) {
                             val chData = lastChannelData.find { it.channel == ch }
                             val detected = if (ch < channelDetected.size) channelDetected[ch] else false
-                            val showWalls = if (chData != null && chData.buffer.isNotEmpty()) {
-                                analyzer.analyzeChannel(chData.buffer, ch).result
+                            // 그래프 벽 표시: lastWallResults에서 가져옴 (선택된 Method 결과와 동일)
+                            val wallPair = if (ch < lastWallResults.size) lastWallResults[ch] else null
+                            val showWalls = if (wallPair != null) {
+                                com.example.medilightv2android.managers.LowEchoResult(
+                                    ant = wallPair.first, post = wallPair.second,
+                                    lowStart = wallPair.first, lowEnd = wallPair.second,
+                                    lowMean = 0.0, urineLen = wallPair.second - wallPair.first,
+                                    score = 0.0, innerPeaks = emptyList()
+                                )
                             } else null
                             Column(verticalArrangement = Arrangement.spacedBy(2.dp)) {
                                 Row(verticalAlignment = Alignment.CenterVertically) {
@@ -499,6 +509,7 @@ fun PlacementGuideView(appState: AppState) {
                         channelUrineLen[i] = urineLens[i]
                     }
                     lastChannelData = channels
+                    lastWallResults = allWalls.toList()
 
                     // Detachment check (미부착 감지)
                     val buffers = channels.sortedBy { it.channel }.map { it.buffer }