Fetch each new article once and measure visible <p> text. If body is below
500 chars (or fetch fails), resolve a Wayback snapshot via the
archive.org/wayback/available API and use that URL for both the og:image
fallback and the posted link. Dedup keys stay derived from the original
URL so paywalled/non-paywalled hits collide as before.
- New: internal/ingestion/article.go (FetchArticleMeta via goquery)
- New: internal/ingestion/wayback.go (ResolveWayback)
- Removed: internal/ingestion/og.go (folded into article.go)
- poller.go: dedup first, then one article fetch, then snapshot fallback
