~x-ai/grok-latest → B (2:5)

Side B lands real product and API substance: cookie-backed themes with POST /theme, auth flows that re-issue the theme cookie, layout/CSS integration, plus item_path_for_api_in_room/forum_thread_web_url wired through rpc with tests so private-room JSON links are correct. Side A mainly deletes the leftover monolithic forum.rs and finishes the forum/ module split (mod, feed, views, etc.), which is lasting structure but largely reorganization without new behavior.