Fail DNS apply early with a clear error when Porkbun secrets are empty

[Copilot]

The apply job failed with 400 API Key Required / APIError: All API requests require an API key or API token. PORKBUN_API_KEY and/or PORKBUN_SECRET_KEY reached the step as empty values, so octoDNS called Porkbun with no credentials. The workflow and config/octodns.yaml wiring is correct. The underlying cause is a missing or empty secret, which this PR cannot fix.

• .github/workflows/dns-apply.yml
  • The octoDNS apply step now checks that both env vars are non-empty before running octodns-sync.
  • If either is empty, it emits a ::error:: annotation naming the secrets and exits 1. This replaces the Porkbun traceback with a message pointing at the actual problem.

if [ -z "$PORKBUN_API_KEY" ] || [ -z "$PORKBUN_SECRET_KEY" ]; then
  echo "::error::PORKBUN_API_KEY and/or PORKBUN_SECRET_KEY are empty. ..."
  exit 1
fi
octodns-sync --config-file=config/octodns.yaml --doit

Needed before the job can pass: set PORKBUN_API_KEY and PORKBUN_SECRET_KEY as repo secrets, or as secrets on the production environment that this job runs in. Also confirm API Access is enabled for api-standards.io in Porkbun. Without that, the job will still fail, now with the clearer error.

dns-plan.yml has the same unguarded step and was left unchanged.