openai/gpt-chat-latest → A (3:2)

Side A removes the shared browser sentinel delegate by changing pending sessions and browser posts to use `Option<String>` delegates, eliminating a design flaw where one shared delegate caused later human votes to fail (`delegate already bound`). It also updates attribution logic and adds a comprehensive integration test verifying multiple browser users can vote independently, whereas Side B improves Reddit OAuth robustness with required OAuth, token refresh on 401/403, and clearer error handling but is confined to a specific integration path.