fix: 도넛차트 recomposition 버그 + Spot 롱프레스 자동측정 + BV 4채널(CH0~CH3)

- bladderLevel.copy() 할당으로 Compose recomposition 트리거 (도넛차트 실시간 갱신)
- Spot 버튼: Button→Box+detectTapGestures (탭=단일, 롱프레스=30초 자동측정)
- startAutoMeasure() + LaunchedEffect 30초 반복 루프
- BV 추정 CH0~CH4(5ch)→CH0~CH3(4ch) 세로 채널만 사용

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

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

@@ -8,6 +8,8 @@ import androidx.compose.material3.OutlinedTextField
 import androidx.compose.foundation.Canvas
 import androidx.compose.foundation.background
 import androidx.compose.foundation.clickable
+import androidx.compose.foundation.gestures.detectTapGestures
+import androidx.compose.ui.input.pointer.pointerInput
 import androidx.compose.foundation.layout.*
 import androidx.compose.foundation.rememberScrollState
 import androidx.compose.foundation.shape.CircleShape
@@ -109,10 +111,10 @@ fun PiezoMonitoringView(appState: AppState) {
                 if (validChannels.isNotEmpty()) {
                     val analysisResult = analyzer.analyzeMultiChannel(validChannels)
 
-                    // Build walls list for BV estimation (5 channels)
-                    val walls: MutableList<Pair<Int, Int>?> = MutableList(5) { null }
+                    // Build walls list for BV estimation (CH0~CH3, 세로 4채널만)
+                    val walls: MutableList<Pair<Int, Int>?> = MutableList(4) { null }
                     for (ch in analysisResult.channels) {
-                        if (ch.channel < 5 && ch.result != null) {
+                        if (ch.channel < 4 && ch.result != null) {
                             walls[ch.channel] = Pair(ch.result.ant, ch.result.post)
                         }
                     }
@@ -142,7 +144,7 @@ fun PiezoMonitoringView(appState: AppState) {
                     val maxVol = appState.piezoSettings.maxVolume.toDouble()
                     val pct = if (maxVol > 0) (lastVolumeMl / maxVol).coerceAtMost(1.0) else 0.0
                     val level = (pct * BladderLevel.MAX_LEVEL).toInt().coerceIn(1, BladderLevel.MAX_LEVEL)
-                    appState.bladderLevel.currentLevel = level
+                    appState.bladderLevel = appState.bladderLevel.copy(currentLevel = level)
                 }
                 isMeasuring = false
                 measureRetryCount = 0
@@ -183,10 +185,25 @@ fun PiezoMonitoringView(appState: AppState) {
         isMeasuring = false
     }
 
+    fun startAutoMeasure() {
+        isAutoMeasuring = true
+        measure()
+    }
+
     fun stopAutoMeasure() {
         isAutoMeasuring = false
     }
 
+    // Auto-measure: repeat every 30s while active
+    LaunchedEffect(isAutoMeasuring) {
+        if (isAutoMeasuring) {
+            while (isAutoMeasuring) {
+                kotlinx.coroutines.delay(30_000)
+                if (isAutoMeasuring && !isMeasuring) measure()
+            }
+        }
+    }
+
     // Setup disconnect handling
     LaunchedEffect(Unit) {
         bleManager.onUnexpectedDisconnect = {
@@ -634,26 +651,29 @@ fun PiezoMonitoringView(appState: AppState) {
                     Text("Catheterize", fontSize = 16.sp, fontWeight = FontWeight.SemiBold, color = MlPrimary)
                 }
 
-                // Spot button
-                Button(
-                    onClick = {
-                        if (isAutoMeasuring) stopAutoMeasure()
-                        else if (!isMeasuring) measure()
-                    },
-                    modifier = Modifier.weight(1f).height(56.dp),
-                    shape = RoundedCornerShape(16.dp),
-                    colors = ButtonDefaults.buttonColors(containerColor = Color.Transparent),
-                    contentPadding = PaddingValues(),
-                    enabled = !isMeasuring || isAutoMeasuring
-                ) {
+                // Spot button (tap = single, long press = auto 30s)
                 Box(
-                        modifier = Modifier.fillMaxSize().background(
+                    modifier = Modifier
+                        .weight(1f)
+                        .height(56.dp)
+                        .clip(RoundedCornerShape(16.dp))
+                        .background(
                             Brush.horizontalGradient(
                                 if (isAutoMeasuring) listOf(Color.Red, Color(0xFFFF9500))
                                 else urgency.gradientColors
-                            ),
-                            RoundedCornerShape(16.dp)
-                        ),
+                            )
+                        )
+                        .pointerInput(isAutoMeasuring, isMeasuring) {
+                            detectTapGestures(
+                                onTap = {
+                                    if (isAutoMeasuring) stopAutoMeasure()
+                                    else if (!isMeasuring) measure()
+                                },
+                                onLongPress = {
+                                    if (!isAutoMeasuring && !isMeasuring) startAutoMeasure()
+                                }
+                            )
+                        },
                     contentAlignment = Alignment.Center
                 ) {
                     Row(verticalAlignment = Alignment.CenterVertically) {
@@ -674,7 +694,6 @@ fun PiezoMonitoringView(appState: AppState) {
                     }
                 }
             }
-            }
 
             Text(
                 if (isAutoMeasuring) "Measuring every 30s" else "Long press Spot for auto-measurement",