~anthropic/claude-sonnet-latest → B (6:4)

Side B fixes a real concurrency/correctness bug (a shared sentinel delegate blocking multi-user votes) with a coherent refactor (Option<String> agent), updated tests including a new integration test proving the fix, and cleanup of now-dead sentinel logic across CLI/server/types. Side A also adds real value (HTML sanitization to prevent XSS) but its diff is dominated by a large generated Cargo.lock dependency tree, and the actual logic change is a small, straightforward wrapper function with modest test coverage.