Add genesis JSON output validator harness with single retry

Wrap the genesis LLM call (Sonnet 4.6 OAuth) in a harness that JSON.parse + schema-validates the proposal array against the meta_engine genesis schema (title length, required fields, change_type enum, solo_time_estimate ≤16, m_a_self_score keys present, reversibility enum). On parse or schema failure, the harness retries once with the validator error appended to the prompt as 'Your previous output failed validation: <err>. Return corrected JSON.' If the second attempt fails, the cycle records status='genesis_malformed' with the raw output for audit, rather than crashing downstream filter_score.

Genesis-induced cycle failures (silent outage class — see fix in commit 0f2d20d for Bedrock Opus 4.6) drop to zero over 60 days. Downstream filter_score.js never receives a malformed proposal in production. Retry rate sits between 5-15% (signal that the validator is firing) but final success rate ≥ 98%.

If the second-retry success rate is <70% over 30 days, the validator is too strict or the model is consistently misreading the schema — degrade to a soft-warn (log but pass through) and review the schema for ambiguity. If retry rate is 0% over 30 days, the validator never fires and provides no value; remove it.

Rejected at the council verdict. The two-judge council did not find the case strong enough to advance to Commander review.