ROUTING: Placement 진입 경로 분기 (Personalization vs Monitoring)

빌드 106 적용: placementFromMonitoring 플래그 + enterPlacementFromMonitoring() /
backFromPlacementGuide() 헬퍼 추가. Personalization → Placement → Monitoring 정방향과
Monitoring → Placement 재진입 경로에서 Back 동작이 올바르게 분기되도록 일괄 정리.

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

app/src/main/java/com/example/medilightv2android/AppState.kt

@@ -27,6 +27,8 @@ class AppState(private val context: Context) {
     var isDevMode by mutableStateOf(false)
     var piezoSettings by mutableStateOf(PiezoSettings())
     var catheterCount = mutableIntStateOf(0)
+    // Placement 진입 경로 분기용 — Monitoring에서 재진입 시 true, Personalization에서 진입 시 false
+    var placementFromMonitoring by mutableStateOf(false)
 
     private val storage = UserStorage.getInstance(context)
     private val historyStore = MeasurementHistoryStore.getInstance(context)
@@ -125,6 +127,7 @@ class AppState(private val context: Context) {
 
     fun personalizationComplete() {
         storage.piezoSettings = piezoSettings
+        placementFromMonitoring = false
         currentScreen = AppScreen.PLACEMENT_GUIDE
     }
 
@@ -140,9 +143,21 @@ class AppState(private val context: Context) {
     fun placementComplete() {
         bladderLevel = BladderLevel(currentLevel = 0, catheterizationThreshold = bladderLevel.catheterizationThreshold)
         storage.bladderLevel = 0
+        placementFromMonitoring = false
         currentScreen = AppScreen.PIEZO_MONITORING
     }
 
+    fun enterPlacementFromMonitoring() {
+        placementFromMonitoring = true
+        currentScreen = AppScreen.PLACEMENT_GUIDE
+    }
+
+    fun backFromPlacementGuide() {
+        currentScreen = if (placementFromMonitoring) AppScreen.PIEZO_MONITORING
+                        else AppScreen.PIEZO_PERSONALIZATION
+        placementFromMonitoring = false
+    }
+
     fun pinSet(pin: String) {
         storage.pin = pin
         storage.hasPin = true