Extract dates from multiple sources:
- SearXNG: publishedDate field from search results
- YouTube: publishedTimeText from InnerTube response
- OG fallback: article:published_time, og:updated_time, date,
dc.date, dcterms.date, sailthru.date meta tags
Date is shown as (YYYY-MM-DD) or relative time after the tag prefix.
OG tags are fetched for date even when title/URL already matched.
Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>