Refactor user and theme management to use BLoC pattern; remove provider classes and integrate new services for user and group functionalities

lib/blocs/group/group_state.dart

@@ -0,0 +1,40 @@
+import 'package:equatable/equatable.dart';
+import '../../data/models/group.dart';
+
+abstract class GroupState extends Equatable {
+  const GroupState();
+
+  @override
+  List<Object?> get props => [];
+}
+
+class GroupInitial extends GroupState {}
+
+class GroupLoading extends GroupState {}
+
+class GroupLoaded extends GroupState {
+  final List<Group> groups;
+
+  const GroupLoaded({required this.groups});
+
+  @override
+  List<Object?> get props => [groups];
+}
+
+class GroupOperationSuccess extends GroupState {
+  final String message;
+
+  const GroupOperationSuccess({required this.message});
+
+  @override
+  List<Object?> get props => [message];
+}
+
+class GroupError extends GroupState {
+  final String message;
+
+  const GroupError({required this.message});
+
+  @override
+  List<Object?> get props => [message];
+}