Add adapter for slog

To help users of this library integrate with their existing systems, we should add a wrapper for the [slog library](https://pkg.go.dev/golang.org/x/exp/slog).

Start by reviewing the existing go-logger package and the linked slog library documentation to understand the adapter boundary. Identify the public entry point where integrations belong and define the supported slog behavior. Done means users can wrap or route slog through this library, with coverage for the adapter's expected behavior.

Written by the indexing model from the issue text.