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

Side B removes dead legacy-projection code paths (dual code for GitDiscovery vs Evidence envelopes), simplifies epoch/commit detail pages to a single source of truth, and updates tests/schema accordingly, reducing long-term maintenance burden. Side A is a solid internal refactor (newtype Deref, CanonicalItemUrl threading) that improves type safety but is more mechanical churn with less architectural simplification than B's removal of an entire legacy compatibility layer.