openai/gpt-chat-latest → A (5:1)

Side A introduces substantial, project-wide functionality: persistent theme selection via validated cookies and a new `/theme` endpoint, propagates theme state through authentication so login no longer drops the theme, and correctly generates room-scoped URLs across RPC responses with dedicated helpers and tests. Side B is a focused UI refinement that adds vote counts to garden compare links, changes the pin HUD into an unpin action, and updates CSS/tests, but its impact is localized compared with A's cross-cutting infrastructure and correctness improvements.