feat(create_category): add state definition

- Add CreateCategoryStatus enum
- Define CreateCategoryState class
- Manage form submission status
- Include form fields and error message
- Add form validation via isFormValid

Author: fulleni

lib/content_management/bloc/create_category/create_category_state.dart

@@ -0,0 +1,57 @@
+part of 'create_category_bloc.dart';
+
+/// Represents the status of the create category operation.
+enum CreateCategoryStatus {
+  /// Initial state.
+  initial,
+
+  /// The form is being submitted.
+  submitting,
+
+  /// The operation completed successfully.
+  success,
+
+  /// An error occurred.
+  failure,
+}
+
+/// The state for the [CreateCategoryBloc].
+final class CreateCategoryState extends Equatable {
+  /// {@macro create_category_state}
+  const CreateCategoryState({
+    this.status = CreateCategoryStatus.initial,
+    this.name = '',
+    this.description = '',
+    this.iconUrl = '',
+    this.errorMessage,
+  });
+
+  final CreateCategoryStatus status;
+  final String name;
+  final String description;
+  final String iconUrl;
+  final String? errorMessage;
+
+  /// Returns true if the form is valid and can be submitted.
+  /// Based on the Category model, only the name is required.
+  bool get isFormValid => name.isNotEmpty;
+
+  CreateCategoryState copyWith({
+    CreateCategoryStatus? status,
+    String? name,
+    String? description,
+    String? iconUrl,
+    String? errorMessage,
+  }) {
+    return CreateCategoryState(
+      status: status ?? this.status,
+      name: name ?? this.name,
+      description: description ?? this.description,
+      iconUrl: iconUrl ?? this.iconUrl,
+      errorMessage: errorMessage,
+    );
+  }
+
+  @override
+  List<Object?> get props => [status, name, description, iconUrl, errorMessage];
+}