fix(server): preserve chosen story parties and validate fixed tactics decks

go/internal/server/deck/story_party.go

@@ -22,22 +22,3 @@ func (s *Store) visibleFieldDeckLocked() []FieldEntry {
 	}
 	return out
 }
-
-// SetStoryParty stores the authored active quest formation using the same
-// character ownership checks as DeckSave. Empty formation keeps player choice.
-func (s *Store) SetStoryParty(entries []DeckEntry) error {
-	if len(entries) == 0 {
-		return nil
-	}
-	if err := validDeck(entries); err != nil {
-		return err
-	}
-	s.mu.Lock()
-	defer s.mu.Unlock()
-	if err := s.validateOwnedDeckLocked(entries); err != nil {
-		return err
-	}
-	next := clone(s.state)
-	next.Deck = append([]DeckEntry(nil), entries...)
-	return s.commit(next)
-}