Format .erl files (or check formatting with --check).
Wraps erlfmt's library API. Exists because the upstream erlfmt Hex package
ships an escript build but no mix task; the project's pre-commit checklist
(CLAUDE.md) references mix erlfmt --check src/ so this task makes that
instruction actually work.
Usage
mix erlfmt --check src/ # exit 0 if clean, exit 1 if any file would change
mix erlfmt --write src/ # rewrite files in placeEither --check or --write is required. Paths can be files or directories;
directories are walked for *.erl files.