Adventure news: add zone_clear event type

gogobee now splits the realm's first-ever clear (zone_first, priority)
from a later repeat (zone_clear, bulletin) so a repeat is never filed as
a first-ever. Handle both:

- renderAdventure: zone_first keeps the "cleared for the very first
  time" headline; zone_clear gets the personal "{subject} clears {zone}"
  headline, sharing the lede. A tier fallback still handles a legacy
  zone_first that predates the split.
- advEventMeta: zone_clear -> "Zone cleared" (distinct from zone_first's
  "First clear"), so a repeat's permalink page and emblem aren't stamped
  "First clear".

The GUID contract is otherwise unchanged: prefix == event_type, so the
permalink label derives correctly. Test: TestRenderZoneTaxonomy.

Deploy this before the matching gogobee change — a zone_clear fact hits
an un-updated Pete as an unknown event_type (400).

internal/web/adventure.go

@@ -153,6 +153,8 @@ func advEventMeta(eventType string) (label, emoji string) {
 		return "Boss down", "🐉"
 	case "zone_first":
 		return "First clear", "🗺️"
+	case "zone_clear":
+		return "Zone cleared", "🗺️"
 	case "death":
 		return "In memoriam", "🪦"
 	case "arrival":
@@ -328,9 +330,12 @@ func renderAdventure(f AdvFact) (headline, lede string, ok bool) {
 	case "boss_kill":
 		return fmt.Sprintf("%s takes down %s again.", f.Subject, f.Boss),
 			fmt.Sprintf("Another clean run in %s today. Routine for %s by now — but still worth a nod.", f.Zone, f.Subject), true
-	case "zone_first":
-		// Realm-first (priority) vs personal (bulletin) share a lede.
-		if f.Tier == "priority" {
+	case "zone_first", "zone_clear":
+		// gogobee splits the realm's first-ever clear (zone_first, priority) from a
+		// later repeat (zone_clear, bulletin); they share a lede but differ in
+		// headline. Fall back to the tier for a legacy zone_first that predates the
+		// split.
+		if f.EventType == "zone_first" || f.Tier == "priority" {
 			headline = fmt.Sprintf("%s cleared for the very first time.", f.Zone)
 		} else {
 			headline = fmt.Sprintf("%s clears %s.", f.Subject, f.Zone)