Adv 2.0 D&D Phase R7: post-completion audit hardening

High-priority fixes from the multi-agent audit of Adventure 2.0:

- Phase 11 nil-deref cluster: zoneOrFallback() helper replaces 8 unsafe
  getZone(_) sites in dnd_zone_cmd.go. Corrupted zone IDs render a
  placeholder instead of panicking.
- Briefing/recap idempotency: deliverBriefing/deliverRecap now claim
  the rollover via a conditional UPDATE. Double-fires from clock skew
  or restart become no-ops; supply burn and day++ no longer reapply.
- Graceful ticker shutdown: AdventurePlugin gains stopCh + Stop(); all
  11 background tickers now select on stopCh in addition to ticker.C.
- Mood decay (§3.2): math.Round(elapsed*2) replaces int() truncation
  so sub-hour gaps decay correctly.
- 24h auto-abandon (§4.3): getActiveZoneRun returns clean slate and
  abandons stale runs whose LastActionAt is over 24h old.
- Respec / auto-migrate orphan cleanup: !respec and the auto-migrated
  draft wipe now abandon active zone runs and expeditions before
  deleting the dnd_character row.
- Phase R combat-link: applyBossDefeatThreat now wired from
  resolveBossRoom (-20 threat); applyRoomCombatThreatForUser adds
  +5/+8 from non-boss/elite kills (§8.1).
- Starvation → forced extraction: briefing-time check forces extract
  with §10.2 coin tax when supplies hit zero.
- GMNat20/Nat1 narration wired into resolveCombatRoom and
  resolveBossRoom (nat-20 takes precedence over nat-1).
- Treasure-undo race: LoadAndDelete on both timer-fire and `undo`
  paths so only one side wins.
- Battle Master: Disarming, Menacing, Parry maneuvers added (3 → 6
  of 10). Remaining 4 (Pushing, Goading, Riposte, Commander's Strike)
  documented inline as needing ally/reaction mechanics the engine
  doesn't model.
- Threat-70 warning: tracked in RegionState["siege_warning_fired"]
  so a drop-and-recross doesn't re-fire the beat.
- region_state JSON decode error now logged via slog.Warn instead
  of silently discarded.

Failing TestProdDB_DnDLayer fixed via option (a): track migrated
characters and only run round-trip / idempotency assertions on those,
skipping pre-existing prod-DB rows accumulated from live bot use.

New tests in dnd_audit_phase_R7_test.go cover: 24h auto-abandon,
briefing double-fire idempotency, threat-70 warning idempotency,
multi-region extract→resume state preservation, and starvation
forced-extraction.

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

internal/plugin/adventure_rival.go

@@ -778,40 +778,45 @@ func (p *AdventurePlugin) rivalChallengeTicker() {
 	// Roll the next challenge interval once. Re-roll after each issued challenge.
 	nextIntervalHours := rivalMinIntervalHours + rand.IntN(rivalMaxIntervalHours-rivalMinIntervalHours+1)
 
-	for range ticker.C {
-		now := time.Now().UTC()
+	for {
+		select {
+		case <-p.stopCh:
+			return
+		case <-ticker.C:
+			now := time.Now().UTC()
 
-		// Only fire on the hour.
-		if now.Minute() != 0 {
-			continue
-		}
+			// Only fire on the hour.
+			if now.Minute() != 0 {
+				continue
+			}
 
-		// Only issue challenges between 08:00 and 22:00 UTC.
-		if now.Hour() < 8 || now.Hour() >= 22 {
-			// Still check for expiry outside challenge hours.
+			// Only issue challenges between 08:00 and 22:00 UTC.
+			if now.Hour() < 8 || now.Hour() >= 22 {
+				// Still check for expiry outside challenge hours.
+				p.expireRivalChallenges()
+				continue
+			}
+
+			// Expire old challenges first.
 			p.expireRivalChallenges()
-			continue
+
+			// Check if enough time has passed since last challenge.
+			last := lastRivalChallengeTime()
+			if !last.IsZero() && now.Sub(last) < time.Duration(nextIntervalHours)*time.Hour {
+				continue
+			}
+
+			// Try to issue a challenge.
+			challenger, challenged := p.selectRivalPair()
+			if challenger == nil || challenged == nil {
+				continue
+			}
+
+			p.issueRivalChallenge(challenger, challenged)
+
+			// Roll a fresh interval for the next challenge.
+			nextIntervalHours = rivalMinIntervalHours + rand.IntN(rivalMaxIntervalHours-rivalMinIntervalHours+1)
 		}
-
-		// Expire old challenges first.
-		p.expireRivalChallenges()
-
-		// Check if enough time has passed since last challenge.
-		last := lastRivalChallengeTime()
-		if !last.IsZero() && now.Sub(last) < time.Duration(nextIntervalHours)*time.Hour {
-			continue
-		}
-
-		// Try to issue a challenge.
-		challenger, challenged := p.selectRivalPair()
-		if challenger == nil || challenged == nil {
-			continue
-		}
-
-		p.issueRivalChallenge(challenger, challenged)
-
-		// Roll a fresh interval for the next challenge.
-		nextIntervalHours = rivalMinIntervalHours + rand.IntN(rivalMaxIntervalHours-rivalMinIntervalHours+1)
 	}
 }