fix: allow out-of-range nice adjustments

Keep nice validation focused on accepting integer values instead of
rejecting values outside the standard -20 to 19 range.

Avoid failing early for values that nice itself accepts and clamps
internally. This gives users behavior that matches the underlying tool
instead of turning a non-error into a transcode.sh usage error.

Update help text and README wording to describe the option as a nice
adjustment, matching the command behavior.

0 files changed, 0 insertions, 0 deletions