Implement the 012-turn-navigation feature that adds a RetreatTurn domain operation and relocates turn controls to a navigation bar at the top of the encounter tracker

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

packages/domain/src/index.ts

@@ -14,12 +14,15 @@ export type {
 	InitiativeSet,
 	MaxHpSet,
 	RoundAdvanced,
+	RoundRetreated,
 	TurnAdvanced,
+	TurnRetreated,
 } from "./events.js";
 export {
 	type RemoveCombatantSuccess,
 	removeCombatant,
 } from "./remove-combatant.js";
+export { retreatTurn } from "./retreat-turn.js";
 export { type SetHpSuccess, setHp } from "./set-hp.js";
 export {
 	type SetInitiativeSuccess,