fixed datetimes in occupancy heatmap. (#301)

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## Description

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## Type of Change

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- [ ] ✨ New feature (non-breaking change which adds functionality)
- [ ] 🛠️ Bug fix (non-breaking change which fixes an issue)
- [ ] ❌ Breaking change (fix or feature that would cause existing
functionality to change)
- [ ] 🧹 Code refactor
- [ ] ✅ Build configuration change
- [ ] 📝 Documentation
- [ ] 🗑️ Chore

lib/pages/analytics/models/occupancy_heat_map_model.dart

@@ -14,14 +14,18 @@ class OccupancyHeatMapModel extends Equatable {
   });
 
   factory OccupancyHeatMapModel.fromJson(Map<String, dynamic> json) {
-    final eventDate = json['event_date'] as String? ?? '${DateTime.now()}';
-    final year = eventDate.split('-')[0];
-    final month = eventDate.split('-')[1];
-    final day = eventDate.split('-')[2];
+    final eventDate = json['event_date'] as String?;
+    final year = eventDate?.split('-')[0];
+    final month = eventDate?.split('-')[1];
+    final day = eventDate?.split('-')[2];
 
     return OccupancyHeatMapModel(
       uuid: json['uuid'] as String? ?? '',
-      eventDate: DateTime(int.parse(year), int.parse(month), int.parse(day)),
+      eventDate: DateTime(
+        int.parse(year ?? '2025'),
+        int.parse(month ?? '1'),
+        int.parse(day ?? '1'),
+      ).toUtc(),
       countTotalPresenceDetected: num.parse(
         json['count_total_presence_detected']?.toString() ?? '0',
       ).toInt(),

lib/pages/analytics/modules/occupancy/widgets/interactive_heat_map.dart

@@ -52,7 +52,7 @@ class _InteractiveHeatMapState extends State<InteractiveHeatMap> {
             color: Colors.transparent,
             child: Transform.translate(
               offset: Offset(-(widget.cellSize * 2.5), -50),
-              child: HeatMapTooltip(date: item.date, value: item.value),
+              child: HeatMapTooltip(date: item.date.toUtc(), value: item.value),
             ),
           ),
         ),

lib/pages/analytics/modules/occupancy/widgets/occupancy_heat_map.dart

@@ -20,14 +20,14 @@ class OccupancyHeatMap extends StatelessWidget {
       : 0;
 
   DateTime _getStartingDate() {
-    final jan1 = DateTime(DateTime.now().year, 1, 1);
+    final jan1 = DateTime(DateTime.now().year, 1, 1).toUtc();
     final startOfWeek = jan1.subtract(Duration(days: jan1.weekday - 1));
     return startOfWeek;
   }
 
   List<OccupancyPaintItem> _generatePaintItems(DateTime startDate) {
     return List.generate(_totalWeeks * 7, (index) {
-      final date = startDate.add(Duration(days: index));
+      final date = startDate.toUtc().add(Duration(days: index));
       final value = heatMapData[date] ?? 0;
       return OccupancyPaintItem(index: index, value: value, date: date);
     });