Implement the 023-clear-encounter feature that adds a clear encounter button with confirmation dialog to remove all combatants and reset round/turn counters, with the cleared state persisting across page refreshes

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

apps/web/src/hooks/use-encounter.ts

@@ -3,6 +3,7 @@ import {
 	addCombatantUseCase,
 	adjustHpUseCase,
 	advanceTurnUseCase,
+	clearEncounterUseCase,
 	editCombatantUseCase,
 	removeCombatantUseCase,
 	retreatTurnUseCase,
@@ -223,6 +224,21 @@ export function useEncounter() {
 		[makeStore],
 	);
 
+	const clearEncounter = useCallback(() => {
+		if (!window.confirm("Clear the entire encounter? This cannot be undone.")) {
+			return;
+		}
+
+		const result = clearEncounterUseCase(makeStore());
+
+		if (isDomainError(result)) {
+			return;
+		}
+
+		nextId.current = 0;
+		setEvents((prev) => [...prev, ...result]);
+	}, [makeStore]);
+
 	const addFromBestiary = useCallback(
 		(creature: Creature) => {
 			const store = makeStore();
@@ -280,6 +296,7 @@ export function useEncounter() {
 		advanceTurn,
 		retreatTurn,
 		addCombatant,
+		clearEncounter,
 		removeCombatant,
 		editCombatant,
 		setInitiative,