Incorrect work with the log level option

[mdigger]

During initialization in the tint.NewHandler, the minimum logging level is copied as a number and then used as an absolute value that cannot be changed.

And in the settings, not just the minimum level is set, but the slog.Leveler interface, which allows you to safely change this value in the future.

var programLevel = new(slog.LevelVar) // Info by default
h := tint.NewHandler(os.Stderr, &tint.HandlerOptions{
    Level: programLevel,
})
slog.SetDefault(slog.New(h))
// ...
programLevel.Set(slog.LevelDebug) // <- DON'T WORK!!!

FYI: https://pkg.go.dev/golang.org/x/exp/slog#hdr-Levels

Accordingly, in the internal handler you also need to replace level slog.Level with slog.Leveler and:

func (h *handler) Enabled(_ context.Context, level slog.Level) bool {
    return level >= h.level.Level()
}