ci: add npm environment to release workflow

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

Author: yamitzky

.github/workflows/release.yml

@@ -24,6 +24,7 @@ jobs:
     needs: release-please
     if: ${{ needs.release-please.outputs.release_created }}
     runs-on: ubuntu-latest
+    environment: npm
     permissions:
       contents: read
       id-token: write