feat: Add cancellation reason handling and display in shift details

apps/mobile/packages/domain/lib/src/entities/shifts/shift_detail.dart

@@ -41,6 +41,7 @@ class ShiftDetail extends Equatable {
     required this.allowClockInOverride,
     this.geofenceRadiusMeters,
     this.nfcTagId,
+    this.cancellationReason,
   });
 
   /// Deserialises from the V2 API JSON response.
@@ -76,6 +77,7 @@ class ShiftDetail extends Equatable {
       allowClockInOverride: json['allowClockInOverride'] as bool? ?? false,
       geofenceRadiusMeters: json['geofenceRadiusMeters'] as int?,
       nfcTagId: json['nfcTagId'] as String?,
+      cancellationReason: json['cancellationReason'] as String?,
     );
   }
 
@@ -157,6 +159,9 @@ class ShiftDetail extends Equatable {
   /// NFC tag identifier for NFC-based clock-in.
   final String? nfcTagId;
 
+  /// Reason the shift was cancelled, if applicable.
+  final String? cancellationReason;
+
   /// Duration of the shift in hours.
   double get durationHours {
     return endTime.difference(startTime).inMinutes / 60;
@@ -194,6 +199,7 @@ class ShiftDetail extends Equatable {
       'allowClockInOverride': allowClockInOverride,
       'geofenceRadiusMeters': geofenceRadiusMeters,
       'nfcTagId': nfcTagId,
+      'cancellationReason': cancellationReason,
     };
   }
 
@@ -225,5 +231,6 @@ class ShiftDetail extends Equatable {
         allowClockInOverride,
         geofenceRadiusMeters,
         nfcTagId,
+        cancellationReason,
       ];
 }