fix: handle tarball already having correct name in release workflow

The headlamp-plugin package command already produces a tarball named
{pkg}-{version}.tar.gz, so the mv command fails when source and
destination are the same file.

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

.github/workflows/release.yaml

@@ -71,7 +71,10 @@ jobs:
           VERSION="${{ inputs.version }}"
           PKG_NAME=$(jq -r .name package.json)
           TARBALL="${PKG_NAME}-${VERSION}.tar.gz"
-          mv *.tar.gz "$TARBALL"
+          ACTUAL=$(ls *.tar.gz)
+          if [ "$ACTUAL" != "$TARBALL" ]; then
+            mv "$ACTUAL" "$TARBALL"
+          fi
           echo "TARBALL=$TARBALL" >> $GITHUB_ENV
           echo "PKG_NAME=$PKG_NAME" >> $GITHUB_ENV