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

Side A delivers a coherent feature (server-rendered, cookie-persisted themes replacing a client-only localStorage hack) plus a real correctness fix for private-room item/URL paths in the API, backed by new unit tests. Side B is a solid but narrower bugfix/cleanup (route rename, better delegate attribution, removing a fallback bug and a dead UI button) with good test updates, but it's smaller in scope and impact than A's broader feature and correctness work.