~x-ai/grok-latest → A (3:1)

Commit A replaces a stub with a complete RedditBroker background worker (OAuth, rate-limit backoff, dedup/TTL, URL mapping, JSON parsers for subreddits/posts, and request-path integration), delivering a real lasting feature. Commit B mainly deletes the demo-counter scaffold and adds a settlement worker plus score cache for votes—valuable concurrency hygiene, but smaller in scope and largely refining existing ranking paths rather than adding new capability.