Verify that a decision supports a claim (Sonnet-4.6 judge)

Given a legal claim + a decision (+ optional Erwägung pinpoint), an independent Sonnet judge determines whether the decision's verbatim text supports the claim. Returns {supports: yes|partial|no|contradicts|unrelated, confidence, supporting_excerpt, qualifying_excerpt, reasoning}. Use when paraphrasing a decision or drawing a proposition from a complex Erwägung — counters the mis-grounding / reasoning-error class measured at 17-33% on commercial legal-RAG tools by Magesh et al., 'Hallucination-Free?', Stanford RegLab, 2024 (cited authority exists but doesn't actually support the proposition).