Refactor storage architecture with modular IndexedDB services

Implements a more flexible, modular approach to IndexedDB storage:
- Introduces IStore interface for dynamic store creation
- Adds specialized services for each entity (BookingService, CustomerService, etc.)
- Moves serialization logic to entity-specific classes
- Improves dependency injection and extensibility

Enables easier addition of new entity types with minimal configuration

src/storage/events/EventStore.ts

@@ -0,0 +1,47 @@
+import { IStore } from '../IStore';
+
+/**
+ * EventStore - IndexedDB ObjectStore definition for calendar events
+ *
+ * Defines schema, indexes, and store creation logic.
+ * Part of modular storage architecture where each entity has its own folder.
+ */
+export class EventStore implements IStore {
+  /** ObjectStore name in IndexedDB (static for backward compatibility) */
+  static readonly STORE_NAME = 'events';
+
+  /** ObjectStore name in IndexedDB (instance property for IStore interface) */
+  readonly storeName = EventStore.STORE_NAME;
+
+  /**
+   * Create the events ObjectStore with indexes
+   * Called during database upgrade (onupgradeneeded)
+   *
+   * @param db - IDBDatabase instance
+   */
+  create(db: IDBDatabase): void {
+    // Create ObjectStore with 'id' as keyPath
+    const store = db.createObjectStore(EventStore.STORE_NAME, { keyPath: 'id' });
+
+    // Index: start (for date range queries)
+    store.createIndex('start', 'start', { unique: false });
+
+    // Index: end (for date range queries)
+    store.createIndex('end', 'end', { unique: false });
+
+    // Index: syncStatus (for filtering by sync state)
+    store.createIndex('syncStatus', 'syncStatus', { unique: false });
+
+    // Index: resourceId (CRITICAL for resource-mode filtering)
+    store.createIndex('resourceId', 'resourceId', { unique: false });
+
+    // Index: customerId (for customer-centric queries)
+    store.createIndex('customerId', 'customerId', { unique: false });
+
+    // Index: bookingId (for event-to-booking lookups)
+    store.createIndex('bookingId', 'bookingId', { unique: false });
+
+    // Compound index: startEnd (for optimized range queries)
+    store.createIndex('startEnd', ['start', 'end'], { unique: false });
+  }
+}