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/player_meta.go

@@ -402,6 +402,13 @@ type PetState struct {
 	MorningDefense     bool
 }
 
+// HasPet returns true if the player has an active pet (arrived, not chased
+// away). Mirrors AdventureCharacter.HasPet() for the cross-file pet-helper
+// flip in L4d.
+func (s PetState) HasPet() bool {
+	return s.Type != "" && s.Arrived && !s.ChasedAway
+}
+
 // petFlagsJSON is the on-disk encoding of the four pet bools. Adding a new
 // flag is an additive JSON field — old rows decode as false.
 type petFlagsJSON struct {