- Added comprehensive performance tests for critical endpoints:
* Health check endpoints (/health, /readyz) - threshold: 10ms
* Authentication endpoints (login: 100ms, register: 200ms)
* Track endpoints (list: 50ms, get: 30ms, create: 500ms)
* Playlist endpoints (list: 50ms, create: 200ms)
* User endpoints (list: 50ms, get: 30ms)
- Includes both performance tests (measuring response times against thresholds)
- Includes benchmarks using Go benchmark framework
- All tests tagged with performance build tag
- Tests use in-memory SQLite for fast execution
