feat(category): add create category BLoC

- Manages category creation state
- Handles form input changes
- Submits new category to repository
- Includes submission status and error states

Author: fulleni

lib/content_management/bloc/create_category/create_category_bloc.dart

@@ -0,0 +1,93 @@
+import 'package:bloc/bloc.dart';
+import 'package:equatable/equatable.dart';
+import 'package:ht_data_repository/ht_data_repository.dart';
+import 'package:ht_shared/ht_shared.dart';
+
+part 'create_category_event.dart';
+part 'create_category_state.dart';
+
+/// A BLoC to manage the state of creating a new category.
+class CreateCategoryBloc
+    extends Bloc<CreateCategoryEvent, CreateCategoryState> {
+  /// {@macro create_category_bloc}
+  CreateCategoryBloc({
+    required HtDataRepository<Category> categoriesRepository,
+  }) : _categoriesRepository = categoriesRepository,
+       super(const CreateCategoryState()) {
+    on<CreateCategoryNameChanged>(_onNameChanged);
+    on<CreateCategoryDescriptionChanged>(_onDescriptionChanged);
+    on<CreateCategoryIconUrlChanged>(_onIconUrlChanged);
+    on<CreateCategorySubmitted>(_onSubmitted);
+  }
+
+  final HtDataRepository<Category> _categoriesRepository;
+
+  void _onNameChanged(
+    CreateCategoryNameChanged event,
+    Emitter<CreateCategoryState> emit,
+  ) {
+    emit(
+      state.copyWith(
+        name: event.name,
+        status: CreateCategoryStatus.initial,
+      ),
+    );
+  }
+
+  void _onDescriptionChanged(
+    CreateCategoryDescriptionChanged event,
+    Emitter<CreateCategoryState> emit,
+  ) {
+    emit(
+      state.copyWith(
+        description: event.description,
+        status: CreateCategoryStatus.initial,
+      ),
+    );
+  }
+
+  void _onIconUrlChanged(
+    CreateCategoryIconUrlChanged event,
+    Emitter<CreateCategoryState> emit,
+  ) {
+    emit(
+      state.copyWith(
+        iconUrl: event.iconUrl,
+        status: CreateCategoryStatus.initial,
+      ),
+    );
+  }
+
+  Future<void> _onSubmitted(
+    CreateCategorySubmitted event,
+    Emitter<CreateCategoryState> emit,
+  ) async {
+    if (!state.isFormValid) return;
+
+    emit(state.copyWith(status: CreateCategoryStatus.submitting));
+    try {
+      final newCategory = Category(
+        name: state.name,
+        description: state.description.isNotEmpty ? state.description : null,
+        iconUrl: state.iconUrl.isNotEmpty ? state.iconUrl : null,
+      );
+
+      await _categoriesRepository.create(item: newCategory);
+      emit(state.copyWith(status: CreateCategoryStatus.success));
+    } on HtHttpException catch (e) {
+      emit(
+        state.copyWith(
+          status: CreateCategoryStatus.failure,
+          errorMessage: e.message,
+        ),
+      );
+    } catch (e) {
+      emit(
+        state.copyWith(
+          status: CreateCategoryStatus.failure,
+          errorMessage: e.toString(),
+        ),
+      );
+    }
+  }
+}