Adventure section: ingest, permalink, digest, emblems, noindex

Pete's side of the Adventure news feed. Receives structured game-event
facts from gogobee, templates them in Pete's warm-reporter voice, and
publishes to a new /adventure section + live Matrix posts.

- adventure.go: bearer ingest + fact-guard + 13 event templates;
  /adventure/{guid} permalink (story.html); per-event SVG emblems at
  /adventure/art/{type}.svg (card image + og:image); NoPush suppresses
  the live Matrix post (cold-start backfill).
- adventure_digest.go: daily BULLETIN roundup at DigestHour (UTC);
  unposted-in-48h = bulletins; marks them digested; per-day ?digest= URL
  avoids canonical dedup.
- config AdventureConfig (enabled/ingest_token/channel/digest_hour);
  web.New takes the seam + a priority poster; started in main.
- adventure theme colors; thumbURL passes through local emblem paths;
  adventure pages are noindex (player-named; gap #5).

Claude-Session: https://claude.ai/code/session_017mEwUmmS7aQTP2NQXj6rUa

internal/web/thumbs.go

@@ -67,6 +67,12 @@ func thumbURL(src string) string {
 	if src == "" {
 		return ""
 	}
+	// Root-relative sources are our own local assets (e.g. the adventure
+	// emblems) — serve them directly; the thumbnailer only handles remote
+	// http(s) images and would 404 a local path.
+	if strings.HasPrefix(src, "/") {
+		return src
+	}
 	return "/img/" + thumbKey(src) + ".avif?u=" + url.QueryEscape(src)
 }