- Add ogStore service for Redis get/set operations
- Extract shared logic: ogHtml (generateHtml, escapeHtml) and articleMeta (relay/gateway fetching)
- Refactor article-og endpoint to read from Redis, try gateway on miss, trigger background refresh
- Add article-og-refresh endpoint for background relay fetching and caching
- Update vercel.json with refresh function config
- Remove WebSocket dependencies from main OG endpoint for faster crawler responses
