implement backend skeleton with MongoDB and Claude AI integration

- Add controllers (Auth, Chat, Event) with placeholder implementations
- Add services (Auth, Chat, Event) with business logic interfaces
- Add repositories with MongoDB/Mongoose models (User, Event, Chat)
- Add middleware for JWT authentication
- Add Claude AI adapter implementing AIProvider interface
- Add utility modules for JWT and password handling
- Add shared types and DTOs for User, CalendarEvent, ChatMessage
- Configure routes with proper endpoint structure
- Update app.ts with dependency injection setup
- Add required dependencies: mongoose, bcrypt, jsonwebtoken, @anthropic-ai/sdk

apps/server/src/ai/ClaudeAdapter.ts

@@ -0,0 +1,18 @@
+import Anthropic from '@anthropic-ai/sdk';
+import { AIProvider, AIContext, AIResponse } from '../services/interfaces';
+
+export class ClaudeAdapter implements AIProvider {
+  private client: Anthropic;
+  private model: string;
+
+  constructor(apiKey?: string, model: string = 'claude-3-haiku-20240307') {
+    this.client = new Anthropic({
+      apiKey: apiKey || process.env.ANTHROPIC_API_KEY,
+    });
+    this.model = model;
+  }
+
+  async processMessage(message: string, context: AIContext): Promise<AIResponse> {
+    throw new Error('Not implemented');
+  }
+}