Add rejected mutation requeue flow in sync UI

lib/features/sync/sync_state.dart

@@ -11,6 +11,7 @@ class SyncState {
     this.lastAttemptAt,
     this.lastError,
     this.lastRejected = const <MutationRejection>[],
+    this.lastRejectedChanges = const <ChangeEnvelope>[],
   });
 
   factory SyncState.fromJson(Map<String, dynamic> json) {
@@ -31,6 +32,13 @@ class SyncState {
                 MutationRejection.fromJson(item as Map<String, dynamic>),
           )
           .toList(growable: false),
+      lastRejectedChanges:
+          (json['lastRejectedChanges'] as List<dynamic>? ?? <dynamic>[])
+              .map(
+                (dynamic item) =>
+                    ChangeEnvelope.fromJson(item as Map<String, dynamic>),
+              )
+              .toList(growable: false),
     );
   }
 
@@ -40,12 +48,14 @@ class SyncState {
   final DateTime? lastAttemptAt;
   final String? lastError;
   final List<MutationRejection> lastRejected;
+  final List<ChangeEnvelope> lastRejectedChanges;
 
   static const Object _unset = Object();
 
   static const SyncState empty = SyncState(
     pendingChanges: <ChangeEnvelope>[],
     lastRejected: <MutationRejection>[],
+    lastRejectedChanges: <ChangeEnvelope>[],
   );
 
   SyncState copyWith({
@@ -55,6 +65,7 @@ class SyncState {
     Object? lastAttemptAt = _unset,
     Object? lastError = _unset,
     List<MutationRejection>? lastRejected,
+    List<ChangeEnvelope>? lastRejectedChanges,
   }) {
     return SyncState(
       cursor: identical(cursor, _unset) ? this.cursor : cursor as String?,
@@ -69,6 +80,7 @@ class SyncState {
           ? this.lastError
           : lastError as String?,
       lastRejected: lastRejected ?? this.lastRejected,
+      lastRejectedChanges: lastRejectedChanges ?? this.lastRejectedChanges,
     );
   }
 
@@ -84,6 +96,9 @@ class SyncState {
       'lastRejected': lastRejected
           .map((MutationRejection rejection) => rejection.toJson())
           .toList(growable: false),
+      'lastRejectedChanges': lastRejectedChanges
+          .map((ChangeEnvelope change) => change.toJson())
+          .toList(growable: false),
     };
   }