Node.js Express API

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Code Style:
- Use TypeScript strict mode with no-explicit-any
- Use async/await — never raw Promise chains or callbacks
- Validate all inputs at the route boundary using Zod
- Use middleware for cross-cutting concerns (auth, logging, error handling)
- Keep route handlers thin — delegate to service functions

Architecture:
- src/routes/ — Express route definitions
- src/services/ — Business logic
- src/repositories/ — Database access layer
- src/middleware/ — Express middleware
- src/types/ — TypeScript type definitions
- src/utils/ — Shared utility functions

Error Handling:
- Create a custom AppError class with statusCode and code properties
- Use a global error handler middleware (must have 4 params)
- Log errors with structured JSON (pino)
- Return consistent error format to clients
- Never expose stack traces in production

Database:
- Use Prisma ORM with typed queries
- Run migrations in CI/CD pipeline
- Use transactions for multi-table operations
- Index foreign keys and frequently queried columns