feat: revamp sensor add flow

lib/features/sensors/sensor_list_screen.dart

@@ -13,6 +13,22 @@ class SensorListScreen extends ConsumerWidget {
   Widget build(BuildContext context, WidgetRef ref) {
     final sensors = ref.watch(sensorsProvider);
 
+    ref.listen(sensorsChannelProvider, (_, next) {
+      next.whenData((msg) {
+        switch (msg['event'] as String?) {
+          case 'sensor_announced':
+            ref.invalidate(sensorsProvider);
+          case 'sensor_enrollment_timeout':
+            ScaffoldMessenger.of(context).showSnackBar(
+              const SnackBar(
+                content: Text('Sensor did not come online in time. '
+                    'Check WiFi credentials and try again.'),
+              ),
+            );
+        }
+      });
+    });
+
     return Scaffold(
       appBar: AppBar(title: const Text('Sensors')),
       body: Column(
@@ -35,16 +51,12 @@ class SensorListScreen extends ConsumerWidget {
                     if (unplaced.isNotEmpty) ...[
                       _SectionHeader(
                           label: 'Unplaced', count: unplaced.length),
-                      ...unplaced.map((s) => _SensorTile(
-                            sensor: s,
-                          )),
+                      ...unplaced.map((s) => _SensorTile(sensor: s)),
                     ],
                     if (placed.isNotEmpty) ...[
                       _SectionHeader(
                           label: 'Placed', count: placed.length),
-                      ...placed.map((s) => _SensorTile(
-                            sensor: s,
-                          )),
+                      ...placed.map((s) => _SensorTile(sensor: s)),
                     ],
                   ],
                 );
@@ -87,22 +99,30 @@ class _SectionHeader extends StatelessWidget {
 }
 
 class _SensorTile extends StatelessWidget {
-  const _SensorTile({required this.sensor, this.isSelected = false});
+  const _SensorTile({required this.sensor});
 
   final Sensor sensor;
-  final bool isSelected;
 
   @override
   Widget build(BuildContext context) {
     return ListTile(
-      selected: isSelected,
       leading: Icon(sensor.isPlaced
           ? Icons.sensors
           : Icons.sensors_off_outlined),
       title: Text(sensor.displayName),
       subtitle: Text(
           sensor.isPlaced ? 'Placed' : 'Not placed on floor plan'),
-      trailing: const Icon(Icons.chevron_right),
+      textColor: sensor.confirmed ? null : Colors.grey,
+      trailing: sensor.confirmed
+          ? const Icon(Icons.chevron_right)
+          : Row(
+              mainAxisSize: MainAxisSize.min,
+              children: const [
+                Icon(Icons.access_time, color: Colors.amber, size: 18),
+                SizedBox(width: 4),
+                Icon(Icons.chevron_right),
+              ],
+            ),
       onTap: () => showSensorDetailSheet(context, sensor.id),
     );
   }