Refactor entity services with hybrid sync pattern

Introduces BaseEntityService and SyncPlugin to eliminate code duplication across entity services

Improves:
- Code reusability through inheritance and composition
- Sync infrastructure for all entity types
- Polymorphic sync status management
- Reduced boilerplate code by ~75%

Supports generic sync for Event, Booking, Customer, and Resource entities

src/storage/customers/CustomerService.ts

@@ -1,108 +1,29 @@
 import { ICustomer } from '../../types/CustomerTypes';
+import { EntityType } from '../../types/CalendarTypes';
 import { CustomerStore } from './CustomerStore';
+import { BaseEntityService } from '../BaseEntityService';
 
 /**
  * CustomerService - CRUD operations for customers in IndexedDB
  *
- * Handles all customer-related database operations.
- * Part of modular storage architecture where each entity has its own service.
+ * ARCHITECTURE:
+ * - Extends BaseEntityService for shared CRUD and sync logic
+ * - No serialization needed (ICustomer has no Date fields)
+ * - Provides customer-specific query methods (by phone, search by name)
  *
- * Note: No serialization needed - ICustomer has no Date fields.
+ * INHERITED METHODS (from BaseEntityService):
+ * - get(id), getAll(), save(entity), delete(id)
+ * - markAsSynced(id), markAsError(id), getSyncStatus(id), getBySyncStatus(status)
+ *
+ * CUSTOMER-SPECIFIC METHODS:
+ * - getByPhone(phone)
+ * - searchByName(searchTerm)
  */
-export class CustomerService {
-  private db: IDBDatabase;
+export class CustomerService extends BaseEntityService<ICustomer> {
+  readonly storeName = CustomerStore.STORE_NAME;
+  readonly entityType: EntityType = 'Customer';
 
-  /**
-   * @param db - IDBDatabase instance (injected dependency)
-   */
-  constructor(db: IDBDatabase) {
-    this.db = db;
-  }
-
-  /**
-   * Get a single customer by ID
-   *
-   * @param id - Customer ID
-   * @returns ICustomer or null if not found
-   */
-  async get(id: string): Promise<ICustomer | null> {
-    return new Promise((resolve, reject) => {
-      const transaction = this.db.transaction([CustomerStore.STORE_NAME], 'readonly');
-      const store = transaction.objectStore(CustomerStore.STORE_NAME);
-      const request = store.get(id);
-
-      request.onsuccess = () => {
-        resolve(request.result || null);
-      };
-
-      request.onerror = () => {
-        reject(new Error(`Failed to get customer ${id}: ${request.error}`));
-      };
-    });
-  }
-
-  /**
-   * Get all customers
-   *
-   * @returns Array of all customers
-   */
-  async getAll(): Promise<ICustomer[]> {
-    return new Promise((resolve, reject) => {
-      const transaction = this.db.transaction([CustomerStore.STORE_NAME], 'readonly');
-      const store = transaction.objectStore(CustomerStore.STORE_NAME);
-      const request = store.getAll();
-
-      request.onsuccess = () => {
-        resolve(request.result as ICustomer[]);
-      };
-
-      request.onerror = () => {
-        reject(new Error(`Failed to get all customers: ${request.error}`));
-      };
-    });
-  }
-
-  /**
-   * Save a customer (create or update)
-   *
-   * @param customer - ICustomer to save
-   */
-  async save(customer: ICustomer): Promise<void> {
-    return new Promise((resolve, reject) => {
-      const transaction = this.db.transaction([CustomerStore.STORE_NAME], 'readwrite');
-      const store = transaction.objectStore(CustomerStore.STORE_NAME);
-      const request = store.put(customer);
-
-      request.onsuccess = () => {
-        resolve();
-      };
-
-      request.onerror = () => {
-        reject(new Error(`Failed to save customer ${customer.id}: ${request.error}`));
-      };
-    });
-  }
-
-  /**
-   * Delete a customer
-   *
-   * @param id - Customer ID to delete
-   */
-  async delete(id: string): Promise<void> {
-    return new Promise((resolve, reject) => {
-      const transaction = this.db.transaction([CustomerStore.STORE_NAME], 'readwrite');
-      const store = transaction.objectStore(CustomerStore.STORE_NAME);
-      const request = store.delete(id);
-
-      request.onsuccess = () => {
-        resolve();
-      };
-
-      request.onerror = () => {
-        reject(new Error(`Failed to delete customer ${id}: ${request.error}`));
-      };
-    });
-  }
+  // No serialization override needed - ICustomer has no Date fields
 
   /**
    * Get customers by phone number
@@ -112,8 +33,8 @@ export class CustomerService {
    */
   async getByPhone(phone: string): Promise<ICustomer[]> {
     return new Promise((resolve, reject) => {
-      const transaction = this.db.transaction([CustomerStore.STORE_NAME], 'readonly');
-      const store = transaction.objectStore(CustomerStore.STORE_NAME);
+      const transaction = this.db.transaction([this.storeName], 'readonly');
+      const store = transaction.objectStore(this.storeName);
       const index = store.index('phone');
       const request = index.getAll(phone);