- Replaced Apollo Server with Mercurius for GraphQL API
- Updated resolvers to use Mercurius-compatible GraphQL implementation
- Migrated from Express to Fastify for server framework
- Improved error handling with GraphQL error extensions
- Added Zod for environment variable validation
- Updated Prisma schema and migrations
- Configured CORS and WebSocket subscriptions
- Simplified GraphQL schema and resolver structure
- Enhanced type safety and code organization
