fix: remove redundant tarball rename in release workflow

The mv was a leftover from when the plugin built in a subdirectory.
Now that source lives at repo root, the tarball is already correctly
named — just verify it exists instead.

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

.github/workflows/release.yaml

@@ -71,7 +71,11 @@ jobs:
           VERSION="${{ inputs.version }}"
           PKG_NAME=$(jq -r .name package.json)
           TARBALL="${PKG_NAME}-${VERSION}.tar.gz"
-          mv *.tar.gz "$TARBALL"
+          if [ ! -f "$TARBALL" ]; then
+            echo "Error: Expected tarball $TARBALL not found"
+            ls -la *.tar.gz 2>/dev/null || echo "No .tar.gz files found"
+            exit 1
+          fi
           echo "TARBALL=$TARBALL" >> $GITHUB_ENV
           echo "PKG_NAME=$PKG_NAME" >> $GITHUB_ENV