Publish, unpublish, or delete many CMS posts at once

Applies one lifecycle action to up to 25 posts in a single request. Each post is processed independently: one failure never aborts the batch, and every id comes back in either succeeded or failed with a machine-readable code. Duplicate ids are deduplicated (first occurrence wins) before processing, so counts.requested reflects the deduplicated set. A 200 means the batch was processed, not that every id succeeded - always inspect failed. The delete action additionally requires the delete:content scope.