go-logging

Structured logging in Go with `log/slog` (Go 1.21+ stdlib). ALWAYS use this skill when adding, reviewing, or debugging logging in Go — choosing a logger, configuring `slog.NewJSONHandler` / `slog.NewTextHandler`, injecting `*slog.Logger` as a dependency, using `slog.With`, `slog.Group`, `LogValuer` for lazy values, propagating loggers through `context.Context`, picking log levels (info/debug/warn/error), or designing observability patterns (USE method, RED method). Pair with go-http for request-scoped logging middleware and go-errors for the "log or return, not both" rule.