fix: use release token for release please labels

[zeno-codebot]

Summary

• use the configured release trigger token for the post-release Release Please label transition
• preserve the default token for read-only release-PR discovery

Validation

• npx vitest run --project unit scripts/release-please-config.test.ts
• node + js-yaml workflow parse
• git diff --check

Root cause

The repository restricts the default GitHub Actions token for issue-label writes. The release trigger token already creates the release and is required for the paired label transition.