v1.5.11 — Schema↔runtime coherence drift gates

48 tests fired every npm test: L3 threshold values must match LOAN_DEFAULTS, every PERSONA_PROMPTS × seniority must contain 5 required clauses + persona anchor + MAX cap in 250-360 range. Structural pins catch benchmark-affecting drift at PR time without live Anthropic credits. Not shipped: actual benchmark rerun (blocked on credit topup). Tests 620 → 668 (+48).