ci: tag HEAD instead of stale COMMIT_REF in puniversald workflow

Companion to the previous dispatch-UI simplification. Removed the
COMMIT_REF plumbing but missed the git tag -a line that still
referenced the now-undefined variable, breaking workflow_dispatch.

Author: mohammeds1992

.github/workflows/release-universal.yml

@@ -87,7 +87,7 @@ jobs:
             git push --delete origin "$FULL_TAG" || true
           fi
 
-          git tag -a "$FULL_TAG" "$COMMIT_REF" -m "Release $FULL_TAG"
+          git tag -a "$FULL_TAG" HEAD -m "Release $FULL_TAG"
           git push origin "$FULL_TAG"
 
       - name: Set up Go