Check pre-commit formatting before adding formatter CI

If a repo commits only through a script that already runs the formatters (alejandra, stylua) before git commit, a formatter CI job will almost never fail. Read the existing workflow and commit scripts before proposing new CI. The remaining gaps are usually linters such as shellcheck for scripts. Run them locally first: if they already pass and the scripts run every day, keeping CI as it is is a fine recommendation. On Codeberg/Forgejo, nix run --inputs-from . nixpkgs#<tool> in a nixos/nix container uses the flake's pinned nixpkgs for those checks.