fix: return to sensors list after cancelling reposition only if you've arrived from there

lib/features/floorplan/floor_plan_screen.dart

@@ -80,6 +80,7 @@ class _FloorPlanScreenState extends ConsumerState<FloorPlanScreen> {
 
   void _cancelPlacement() {
     ref.read(sensorPlacementProvider.notifier).state = null;
+    ref.read(sensorPlacementOriginSensorsProvider.notifier).state = false;
   }
 
   @override
@@ -135,8 +136,9 @@ class _FloorPlanScreenState extends ConsumerState<FloorPlanScreen> {
       canPop: placingSensor == null,
       onPopInvokedWithResult: (didPop, _) {
         if (!didPop && placingSensor != null) {
+          final fromSensors = ref.read(sensorPlacementOriginSensorsProvider);
           _cancelPlacement();
-          context.go('/sensors');
+          if (fromSensors) context.go('/sensors');
         }
       },
       child: Scaffold(
@@ -276,8 +278,10 @@ class _FloorPlanScreenState extends ConsumerState<FloorPlanScreen> {
                         sensor: placingSensor,
                         onPlace: () => _confirmPlacement(placingSensor),
                         onCancel: () {
+                          final fromSensors =
+                              ref.read(sensorPlacementOriginSensorsProvider);
                           _cancelPlacement();
-                          context.go('/sensors');
+                          if (fromSensors) context.go('/sensors');
                         },
                       ),
                     ),

lib/features/sensors/sensor_detail_sheet.dart

@@ -77,7 +77,10 @@ class _SensorDetailSheetState extends ConsumerState<SensorDetailSheet> {
 
   void _placeOnFloorPlan(BuildContext context, Sensor sensor) {
     final router = GoRouter.of(context);
+    final fromSensors =
+        router.routeInformationProvider.value.uri.path == '/sensors';
     ref.read(sensorPlacementProvider.notifier).state = sensor;
+    ref.read(sensorPlacementOriginSensorsProvider.notifier).state = fromSensors;
     Navigator.of(context, rootNavigator: true).pop();
     router.go('/floorplan');
   }

lib/providers.dart

@@ -166,6 +166,10 @@ final tagProvider =
 /// center-dot placement flow. Cleared on Place, Cancel, or back navigation.
 final sensorPlacementProvider = StateProvider<Sensor?>((ref) => null);
 
+/// True when placement mode was initiated from the sensors list tab.
+/// Used by FloorPlanScreen to decide whether to navigate back on cancel.
+final sensorPlacementOriginSensorsProvider = StateProvider<bool>((ref) => false);
+
 final floorPlanModeProvider =
     StateProvider<FloorPlanMode>((ref) => FloorPlanMode.view);