feat: Implement staff availability feature with BLoC architecture

- Created AvailabilityPage with UI for managing staff availability.
- Integrated BLoC for state management, including LoadAvailability and ToggleDayStatus events.
- Added quick set options for availability (All Week, Weekdays, Weekends, Clear All).
- Implemented week navigation and day selection with visual feedback.
- Developed time slot management for each day, allowing toggling of availability.
- Established StaffAvailabilityModule for dependency injection and routing.
- Updated pubspec.yaml with necessary dependencies for the feature.

apps/mobile/packages/data_connect/lib/src/mocks/staff_repository_mock.dart

@@ -36,4 +36,23 @@ class StaffRepositoryMock {
     await Future.delayed(const Duration(milliseconds: 500));
     return staff;
   }
+
+  // Mock Availability Data Store
+  final Map<String, dynamic> _mockAvailability = {};
+
+  Future<Map<String, dynamic>> getAvailability(String userId, DateTime start, DateTime end) async {
+    await Future.delayed(const Duration(milliseconds: 300));
+    // Return mock structure: Date ISO String -> { isAvailable: bool, slots: { id: bool } }
+    
+    // Auto-generate some data if empty
+    if (_mockAvailability.isEmpty) {
+      // Just return empty, let the caller handle defaults
+    }
+    return _mockAvailability;
+  }
+
+  Future<void> updateAvailability(String userId, String dateIso, Map<String, dynamic> data) async {
+    await Future.delayed(const Duration(milliseconds: 200));
+    _mockAvailability[dateIso] = data;
+  }
 }