Add voiding diary view + home icon navigation

VoidingDiaryView:
- Date-grouped record list (grouped by day)
- Shows volume/awake/sleep with icons and colors
- Method badge (수기/음성/카메라)
- Delete with confirmation dialog
- Total record count footer

Navigation changes:
- Piezo screen: ArrowBack → Home icon (집 아이콘)
- Piezo screen: 배뇨일지 icon (Description) added next to home
- NIRS screen: ArrowBack → Home icon
- AppScreen.VOIDING_DIARY route added to Crossfade navigation
- VoidingDiaryView navigates back to HOME

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

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

@@ -13,7 +13,8 @@ import com.example.medilightv2android.services.*
 enum class AppScreen {
     ONBOARDING, REGISTRATION, HOME, SENSOR_SELECT, DEVICE_SCAN,
     NIRS_CALIBRATION, PIEZO_PERSONALIZATION, PIN_SETUP, PIN_ENTRY,
-    VIVAMYO_MONITORING, PIEZO_MONITORING, MEASUREMENT_HISTORY
+    VIVAMYO_MONITORING, PIEZO_MONITORING, MEASUREMENT_HISTORY,
+    VOIDING_DIARY
 }
 
 class AppState(private val context: Context) {