Build provider-pack transport layers once, reuse verified image files in private directories, and upload only missing layers. Preserve archive integrity checks and directory fallback on unsupported hosts.
Verified with 44 focused tests, all 48 main CI jobs, cloud Docker Runner checks, and Greptile 5/5 on the merged head.
Co-Authored-By: Paperclip <noreply@paperclip.ing>
