Verifies the trustworthiness of research notes produced by research-search. Use when the user asks to verify / cross-check / audit a research-raw.md file, when research-search has just finished, when the user asks "is this research reliable?", or when explicitly invoked via /research-verify. Cross-checks facts across multiple sources, flags contradictions, validates publication dates against today's date, and confirms every source URL actually resolves via WebFetch. Writes the result to research-verified.md with per-fact metadata (primary/secondary, date freshness, cross-check status, URL liveness) and a flag summary at the top.
