fix(gappsscript): surface deployment version in list_deployments

list_deployments read description from the top level and never showed the
bound version number, so there was no programmatic way to confirm which
version a deployment actually serves. Both fields live under
deploymentConfig in the API response.

Read description and versionNumber from deploymentConfig (falling back to
any top-level description), and show the version per deployment. HEAD
deployments (no versionNumber) are labelled 'HEAD (latest)' rather than
shown blank.

The core update-body wrapper bug from #922 was already fixed in f174989
(#836); this addresses the issue's remaining ask — making deployment
version state verifiable via the API.

Closes #922

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>