Adds comprehensive mock data repositories and seeding infrastructure

Implements polymorphic data seeding mechanism for initial application setup

- Adds Mock repositories for Event, Booking, Customer, and Resource entities
- Creates DataSeeder to automatically populate IndexedDB from JSON sources
- Enhances index.ts initialization process with data seeding step
- Adds mock JSON data files for comprehensive test data

Improves offline-first and development testing capabilities

src/repositories/MockResourceRepository.ts

@@ -0,0 +1,80 @@
+import { IResource, ResourceType } from '../types/ResourceTypes';
+import { EntityType } from '../types/CalendarTypes';
+import { IApiRepository } from './IApiRepository';
+
+interface RawResourceData {
+  id: string;
+  name: string;
+  displayName: string;
+  type: string;
+  avatarUrl?: string;
+  color?: string;
+  isActive?: boolean;
+  metadata?: Record<string, any>;
+  [key: string]: unknown;
+}
+
+/**
+ * MockResourceRepository - Loads resource data from local JSON file
+ *
+ * This repository implementation fetches mock resource data from a static JSON file.
+ * Used for development and testing instead of API calls.
+ *
+ * Data Source: data/mock-resources.json
+ *
+ * NOTE: Create/Update/Delete operations are not supported - throws errors.
+ * Only fetchAll() is implemented for loading initial mock data.
+ */
+export class MockResourceRepository implements IApiRepository<IResource> {
+  public readonly entityType: EntityType = 'Resource';
+  private readonly dataUrl = 'data/mock-resources.json';
+
+  /**
+   * Fetch all resources from mock JSON file
+   */
+  public async fetchAll(): Promise<IResource[]> {
+    try {
+      const response = await fetch(this.dataUrl);
+
+      if (!response.ok) {
+        throw new Error(`Failed to load mock resources: ${response.status} ${response.statusText}`);
+      }
+
+      const rawData: RawResourceData[] = await response.json();
+
+      return this.processResourceData(rawData);
+    } catch (error) {
+      console.error('Failed to load resource data:', error);
+      throw error;
+    }
+  }
+
+  /**
+   * NOT SUPPORTED - MockResourceRepository is read-only
+   */
+  public async sendCreate(resource: IResource): Promise<IResource> {
+    throw new Error('MockResourceRepository does not support sendCreate. Mock data is read-only.');
+  }
+
+  /**
+   * NOT SUPPORTED - MockResourceRepository is read-only
+   */
+  public async sendUpdate(id: string, updates: Partial<IResource>): Promise<IResource> {
+    throw new Error('MockResourceRepository does not support sendUpdate. Mock data is read-only.');
+  }
+
+  /**
+   * NOT SUPPORTED - MockResourceRepository is read-only
+   */
+  public async sendDelete(id: string): Promise<void> {
+    throw new Error('MockResourceRepository does not support sendDelete. Mock data is read-only.');
+  }
+
+  private processResourceData(data: RawResourceData[]): IResource[] {
+    return data.map((resource): IResource => ({
+      ...resource,
+      type: resource.type as ResourceType,
+      syncStatus: 'synced' as const
+    }));
+  }
+}