Trim whitespace/newlines from registry credentials before push

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>

.forgejo/workflows/build.yml

@@ -52,6 +52,9 @@ jobs:
             quay.io/buildah/stable:latest \
             bash -c '
               set -euo pipefail
+              # Secrets pasted with stray whitespace/newlines break registry auth
+              RUSER="$(printf "%s" "$RUSER" | tr -d " \r\n")"
+              RTOKEN="$(printf "%s" "$RTOKEN" | tr -d " \r\n")"
               # Use the fast kernel overlay driver instead of fuse-overlayfs
               # (we are privileged, so this works — and is ~50x faster on
               # the millions of small files in the OSTree base)