Auto-add all local sources on release

I just did a bit of patching for a package and when the build finally worked the patchfile was missing:

$ pkgctl build --rebuild --offload --inspect failure --release --staging --db-update --message "Rebuild for boost 1.87.0"
==> Releasing luminancehdr to extra-staging
[...]
error: pathspec 'luminancehdr-fix-boost-1.87.0-compilation.patch' did not match any file(s) known to git
Did you forget to 'git add'?
==> ERROR: luminancehdr-fix-boost-1.87.0-compilation.patch is not under version control

I think it would make sense to auto-add all files to git that are part of the sources=(...) array and are not specified as remote.