Act 3 boss win can export empty map_select instead of victory

[CyberBarbarian]

During a high-HP headless Ironclad coverage run, an Act 3 Queen boss win reached a terminal game result internally but exported an actionable-looking empty map selection instead of a victory terminal state.

Focused observed state after killing Queen:

{
  decision: map_select,
  context: {
    act: 3,
    floor: 15,
    room_type: null,
    boss: { id: QUEEN_BOSS, name: Queen }
  },
  choices: []
}

Relevant log shape:

CHARACTER.IRONCLAD fought ENCOUNTER.QUEEN_BOSS ... WON
Epoch obtained for completing Act 3
Boss defeated, entering next act
EnterNextAct: Object reference not set to an instance of an object.

Expected: after the final Act 3 boss is won, the headless API should expose a terminal victory state, for example decision=game_over with victory=true, or an equivalent explicit terminal result. It should not return map_select with no legal choices.

There was also a headless UI cleanup NRE around Queen death presentation (NCombatRoom.Instance.GetCreatureNode(...).SpineAnimation.SetAnimation(...)). In the local fork I handled that separately by preserving Queen's original gameplay AfterDeath path and stripping only the headless-unsafe UI cleanup, then reporting final boss victory before trying to enter a non-existent next act.

Optional fork reference: CyberBarbarian@e0ec72c