- Add TestMode, RateLimitEnabled, RequestsPerMinute to Config
- Add getEnvBool() and getEnvInt() helper functions
- Update rate limiter to support enabled/disabled state
- Pass test environment variables through docker-compose
- Configure rate limiter dynamically in main.go
This allows disabling rate limiting for integration testing while
maintaining security in production environments.
- Add rate limiter middleware (10 requests/minute per IP)
- Apply rate limiting to POST /api/auth/register and /api/auth/login
- Prevents brute force attacks and registration spam
- Automatic cleanup of old request records
Closes security issue: No rate limiting on auth endpoints