docs(ouroboros): record feed-moat completion blocker

[minsing-jin]

Summary

• documents the strict Ouroboros completion gap for the latest Hedwig feed-moat lineage
• records the evaluation, Ralph, and serial evolve_step attempts made after OOM recovery
• captures the formal terminal blocker instead of incorrectly claiming PASS/convergence

Verification

• python3 -m pytest -q tests/test_issue27_ouroboros_completion.py
• python3 -m pytest -q tests/test_personal_algorithm_engine.py tests/test_ambient_delivery_surfaces.py tests/test_issue19_evidence_package.py tests/test_issue27_ouroboros_completion.py
• .venv/bin/python -m pytest -q

Full-suite result: 726 passed, 1 warning in 23.38s

Closes #27