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

packages/shared/package.json

@@ -2,7 +2,10 @@
   "name": "@caldav/shared",
   "version": "1.0.0",
   "private": true,
+  "main": "./src/index.ts",
+  "types": "./src/index.ts",
   "exports": {
+    ".": "./src/index.ts",
     "./*": "./src/*"
   }
 }