fix: restore resumable complete compat fields

[rabble]

Summary

• add sha256, size, contentType, thumbnailUrl, and dim back to resumable complete responses
• preserve the newer url, fallbackUrl, and streaming fields for direct clients
• restore compatibility with divine-blossom's existing complete-response parser

Verification

• cargo test complete_session_returns_public_descriptor_fields
• cargo test -q
• live smoke test showed media.divine.video failing on missing sha256 while upload.divine.video returned only url/fallbackUrl/streaming