docs(architecture/embeddings): verify Job Structure table (`attempt` field)

[jack-arturo]

Surfaced by the docs audit in #178 (verified against automem@ebcf5f16).

The Job Structure table (Queue-Based Processing) lists memory_id, content, attempt: int. Code inspection of runtime_pipeline.py@ebcf5f16 suggests jobs may be stored as (memory_id, content) tuples, not dicts with an attempt field — the "re-queue if attempt < 3" logic may be a worker-local counter rather than a job field. Could not confirm definitively during the audit.

Confirm against runtime_pipeline.py and correct the Job Structure / Error Handling tables if needed. #178 shipped the verified fixes (SHA links, VOYAGE_MODEL configurability) and left this flagged.