fix: 그래프 Method 동기화, Spot 쿨다운, 스캔 캐릭터 센터링

도넛차트:
- Developer Tools 그래프: 선택된 Method(A/B/C)로 분석 표시 (기존 B 고정 → 동기화)
- Spot 버튼: 1.5초 쿨다운 (연속 탭 방지, 기기 회복 시간 확보)

DeviceScan:
- 스캐닝 캐릭터 가운데 정렬 (.fillMaxWidth()) + 크기 140→180dp

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

app/src/main/java/com/example/medilightv2android/ui/views/connection/DeviceScanView.kt

@@ -200,11 +200,11 @@ fun DeviceScanView(appState: AppState) {
         // Device list
         if (filteredDevices.isEmpty() && isScanning) {
             Column(
-                modifier = Modifier.weight(1f),
+                modifier = Modifier.weight(1f).fillMaxWidth(),
                 horizontalAlignment = Alignment.CenterHorizontally,
                 verticalArrangement = Arrangement.Center
             ) {
-                BladdyIdleRiveView(size = 140.dp)
+                BladdyIdleRiveView(size = 180.dp)
                 Spacer(modifier = Modifier.height(16.dp))
                 Text("Scanning...", color = MlSecondaryText)
             }

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

@@ -795,10 +795,17 @@ fun PiezoMonitoringView(appState: AppState) {
                     }
                 }
 
-                // Spot (single measurement)
+                // Spot (single measurement, 1.5초 쿨다운)
+                var spotCooldown by remember { mutableStateOf(false) }
                 Button(
-                    onClick = { if (!isMeasuring && !isAutoMeasuring) measure() },
-                    enabled = !isMeasuring && !isAutoMeasuring,
+                    onClick = {
+                        if (!isMeasuring && !isAutoMeasuring && !spotCooldown) {
+                            measure()
+                            spotCooldown = true
+                            handler.postDelayed({ spotCooldown = false }, 1500)
+                        }
+                    },
+                    enabled = !isMeasuring && !isAutoMeasuring && !spotCooldown,
                     modifier = Modifier.weight(1f).height(56.dp),
                     shape = RoundedCornerShape(14.dp),
                     colors = ButtonDefaults.buttonColors(
@@ -1078,7 +1085,14 @@ private fun ChannelPanel(
                 }
             } else {
                 // Zone indicator
-                val analyses = lastMultiChannelResult.map { analyzer.analyzeChannel(it.buffer, it.channel) }
+                val curMethod = com.example.medilightv2android.managers.GreenZoneConstants.detectionMethod
+                val analyzerAPanel = com.example.medilightv2android.managers.PiezoEchoAnalyzerA.shared
+                val analyses = lastMultiChannelResult.map { chData ->
+                    when (curMethod) {
+                        com.example.medilightv2android.managers.DetectionMethod.METHOD_A -> analyzerAPanel.analyzeChannel(chData.buffer, chData.channel)
+                        else -> analyzer.analyzeChannel(chData.buffer, chData.channel)
+                    }
+                }
                 val detectedCount = analyses.count { it.isValid }
                 val zoneColor = when {
                     detectedCount >= 4 -> Color.Green
@@ -1134,7 +1148,10 @@ private fun ChannelPanel(
 
                 // Per-channel waveforms
                 for (chData in lastMultiChannelResult.filter { it.buffer.isNotEmpty() }) {
-                    val chAnalysis = analyzer.analyzeChannel(chData.buffer, chData.channel)
+                    val chAnalysis = when (curMethod) {
+                        com.example.medilightv2android.managers.DetectionMethod.METHOD_A -> analyzerAPanel.analyzeChannel(chData.buffer, chData.channel)
+                        else -> analyzer.analyzeChannel(chData.buffer, chData.channel)
+                    }
 
                     Column(verticalArrangement = Arrangement.spacedBy(3.dp)) {
                         // Channel header