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/dnd_zone_narration.go

@@ -3,6 +3,7 @@ package plugin
 import (
 	"fmt"
 	"hash/fnv"
+	"math"
 	"time"
 
 	"gogobee/internal/db"
@@ -465,12 +466,18 @@ func applyMoodEvent(runID string, ev GMMoodEvent) (int, error) {
 // Design doc §3.2: "Mood decays toward 50 at a rate of ±2 per hour
 // (passive rebalancing)." Long-idle runs reset toward neutral.
 func passiveDecayMood(score int, lastTouched, now time.Time) int {
-	hours := int(now.Sub(lastTouched).Hours())
-	if hours <= 0 {
+	elapsedHours := now.Sub(lastTouched).Hours()
+	if elapsedHours <= 0 {
+		return clampMood(score)
+	}
+	const ratePerHour = 2.0
+	// Round to nearest unit so a 30-minute gap decays 1, a 12-minute
+	// gap decays 0. Avoids the truncation bug where any sub-hour gap
+	// produced no decay.
+	drift := int(math.Round(elapsedHours * ratePerHour))
+	if drift <= 0 {
 		return clampMood(score)
 	}
-	const ratePerHour = 2
-	drift := hours * ratePerHour
 	switch {
 	case score > 50:
 		score -= drift