[jioffe502]

Summary

Follow-up to #2794. Graph rows already carry one typed embedding column; this removes the last nested copy point: client VDB records now hold the vector at the top level.

# before                                   # after
{"document_type": "text",                  {"document_type": "text",
 "metadata": {"embedding": [...],           "embedding": [...],
              "content": "...", ...}}       "metadata": {"content": "...", ...}}

Scope (breaking):

• to_client_vdb_records writes record["embedding"]; readers lancedb._create_lancedb_result, lancedb_collections._collection_rows, and the missing-embedding check in to_client_vdb_records read only that. No fallback to metadata["embedding"]; code that builds records by hand for LanceDB.run must move the vector.
• MetadataSchema.embedding is removed.
• Docs (vdbs.md, content-metadata.md) and examples/building_vdb_operator.ipynb updated; test fixtures moved to the new shape.

Unchanged: values stored in LanceDB (vector column, float32), graph-row columns, retrieval.

Tests: VDB / LanceDB / service / ingest / records / embedding-input suites: 1680 passed, 8 skipped (CPU-only). black 25.9.0 and flake8 7.3.0 clean on touched files.

Link to Devin session: https://nvidia-cloud.devinenterprise.com/sessions/34802976322840ce95c617ad48813bcd
Open in Devin Desktop: https://nvidia-cloud.devinenterprise.com/desktop/session/34802976322840ce95c617ad48813bcd?variant=devin
Requested by: @jioffe502

[devin-ai-integration]

I'll fix CI failures and address comments from users with write access. I'll skip comments containing "(aside)".

• Disable automatic comment, CI, and merge conflict monitoring