openai/gpt-5.2-chat → A (3:1)

Side A introduces a full server-backed theme system (new /theme route, cookie normalization, layout changes, and propagation through all HTML handlers) and adds room-aware URL handling across RPC via `item_path_for_api_in_room` and `forum_thread_web_url`, affecting many endpoints and responses. Side B mainly enhances the garden UI with vote counts and a HUD unpin form plus related CSS/tests, which is valuable UX polish but narrower in scope and architectural impact than A’s cross-cutting design changes.