Allow adoption of opaque Markdown records

[callumalpass]

Summary

• stop rejecting malformed frontmatter while capturing a local authority for adoption
• upload exact Markdown documents and let the shared Connect/mdbase-rs opaque-record contract classify them
• vendor the merged Connect SDK that preserves malformed and non-mapping frontmatter losslessly
• keep the adoption phase accurate until local snapshot capture succeeds
• cover invalid YAML adoption and update resource fixtures for exact revision validation

Validation

• npm test (38 tests)
• npm run check:mobile