Adds WithSlog(logger) option wrapping gin-contrib/slog for structured
request logging via Go's standard log/slog package. Logs method, path,
status code, latency, and client IP for every request. Falls back to
slog.Default() when nil is passed.
Co-Authored-By: Virgil <virgil@lethean.io>
Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>