Adventure news: fix posting gates, digest counts, and section gating

- Don't post adventure beats when posting.enabled=false (PostNow ignores the flag)
- Keep the adventure channel out of the round-robin rotation so it can't steal bulletins from the digest
- no_push now retires a fact against the digest, not just the live post
- Default a missing occurred_at to now instead of the Unix epoch
- Keep protocol-relative image URLs on the guarded thumbnailer
- Make digest_hour=0 (midnight UTC) settable
- Quote the true window total in the digest, not the truncated slice
- Hide the Adventure section entirely when it's disabled

main.go

@@ -248,6 +248,13 @@ func main() {
 	if postingEnabled && roundRobinMode {
 		channelNames := make([]string, 0, len(cfg.Matrix.Channels))
 		for name := range cfg.Matrix.Channels {
+			// The adventure channel drives its own posting: priority beats go
+			// live at ingest, bulletins wait for the daily digest. Leaving it in
+			// the rotation would let the scheduler post bulletins one-by-one
+			// (they're "classified, not yet posted") and steal them from the digest.
+			if cfg.Adventure.Enabled && name == cfg.Adventure.Channel {
+				continue
+			}
 			channelNames = append(channelNames, name)
 		}
 		rr := scheduler.New(channelNames, cfg.Posting.RoundRobin.IntervalHours, queue)
@@ -260,16 +267,22 @@ func main() {
 
 	// Adapter: the web ingest handler posts priority adventure beats live to
 	// Matrix through the same queue everything else uses (bypasses pacing).
-	advPost := func(p web.AdvPost) {
-		queue.PostNow(poster.QueueItem{
-			GUID:       p.GUID,
-			Headline:   p.Headline,
-			Lede:       p.Lede,
-			ImageURL:   p.ImageURL,
-			ArticleURL: p.ArticleURL,
-			Source:     p.Source,
-			Channel:    p.Channel,
-		})
+	// PostNow doesn't consult posting.enabled, so gate here: with posting off,
+	// adventure stays website-only like every other channel (nil poster also
+	// keeps the digest loop from starting).
+	var advPost web.PriorityPoster
+	if postingEnabled {
+		advPost = func(p web.AdvPost) {
+			queue.PostNow(poster.QueueItem{
+				GUID:       p.GUID,
+				Headline:   p.Headline,
+				Lede:       p.Lede,
+				ImageURL:   p.ImageURL,
+				ArticleURL: p.ArticleURL,
+				Source:     p.Source,
+				Channel:    p.Channel,
+			})
+		}
 	}
 
 	// Start the read-only web UI alongside the Matrix bot.