Drop LWN subscriber-only articles instead of stamping paywalled

LWN's subscriber-only articles have no public version reachable by
archive snapshots or bypass UAs, so stamping them as paywalled produces
clicks that always dead-end. Detect the marker text and skip ingestion
entirely.

internal/ingestion/poller.go

@@ -137,6 +137,17 @@ func (p *Poller) pollOnceWithErr(ctx context.Context, src config.SourceConfig) e
 		// swapping in a stale snapshot for a transient blip is worse than
 		// posting the live link.
 		meta := FetchArticleMeta(originalURL)
+		// Some sources (e.g. LWN's subscriber-only articles) have no public
+		// version reachable by any workaround. Drop these from view entirely
+		// rather than stamping them as paywalled.
+		if meta.SubscriberOnly {
+			// No DB row written, so the next poll will re-fetch and re-detect
+			// this URL — fine in practice since LWN's feed is tiny and the
+			// alternative (a tombstone row) leaks into every story query.
+			slog.Info("dropping subscriber-only story",
+				"guid", items[i].GUID, "url", originalURL, "source", src.Name)
+			continue
+		}
 		gated := meta.Gated() || (meta.Fetched && meta.BodyChars < PaywallBodyThreshold)
 		// paywalled tracks whether the link the user will click is still
 		// gated — i.e. gating was detected AND no archive workaround worked.