Implement the 016-combatant-ac feature that adds an optional Armor Class field to combatants with shield icon display and inline editing in the encounter tracker

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

packages/domain/src/index.ts

@@ -6,6 +6,7 @@ export {
 	editCombatant,
 } from "./edit-combatant.js";
 export type {
+	AcSet,
 	CombatantAdded,
 	CombatantRemoved,
 	CombatantUpdated,
@@ -24,6 +25,7 @@ export {
 	removeCombatant,
 } from "./remove-combatant.js";
 export { retreatTurn } from "./retreat-turn.js";
+export { type SetAcSuccess, setAc } from "./set-ac.js";
 export { type SetHpSuccess, setHp } from "./set-hp.js";
 export {
 	type SetInitiativeSuccess,