refactor: split the services to multiple service classes (#202)

e2e/items.spec.ts

@@ -0,0 +1,7 @@
+import { test, expect, Page } from '@playwright/test';
+
+test.describe('item', () => {
+  test('should validate all required fields.', () => {});
+  test('should save the item successfully.', () => {});
+  test('should item code be unqiue.', () => {});
+});