The mockLogger's errors slice was being accessed concurrently from
multiple goroutines (the error bus consumer and the test goroutine),
causing race conditions when running tests with the race detector.
Added sync.Mutex to protect the errors slice and proper locking when
accessing it in test assertions.
- Fix error return value checks (errcheck)
- Fix unused parameters by using underscore prefix
- Add missing package comments to all packages
- Fix context key type issue in middleware (use typed contextKey)
- Replace deprecated trace.NewNoopTracerProvider with noop.NewTracerProvider
- Fix embedded field selector in database client
- Remove trailing whitespace
- Remove revive linter (as requested) to avoid stuttering warnings for public API interfaces
All linting and formatting checks now pass.
