Adv 2.0 L4d reader flip: pet helpers off AdvCharacter to PetState

All ten helpers in adventure_pets.go now take PetState (or *PetState
for petGrantXP) instead of *AdventureCharacter. mistyHousingHint takes
raw NPC counters since Misty fields stay on AdvCharacter for a later
phase. mistyReactivatePet returns bool; caller flips both stores.

DeathTransitionParams gained Pet PetState so combat_bridge no longer
touches the DB; arena caller loads PetState. PetState.HasPet() mirrors
AdvCharacter's. petMidnightCheck loads PetState per char.

L4 grep-empty exit criterion now holds for adventure_pets.go.

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

internal/plugin/adventure_scheduler.go

@@ -116,13 +116,14 @@ func (p *AdventurePlugin) sendMorningDMs() {
 
 		// Pet arrival check (fires before normal morning DM)
 		house, _ := loadHouseState(char.UserID)
-		if petShouldArrive(&char, house) {
+		pet, _ := loadPetState(char.UserID)
+		if petShouldArrive(pet, house) {
 			p.petArrivalDM(char.UserID)
 			continue
 		}
 
 		// Morning pet event
-		petEvent := petMorningEvent(&char)
+		petEvent := petMorningEvent(pet)
 		if petEvent != "" {
 			char.PetMorningDefense = true
 			_ = saveAdvCharacter(&char)