T007–T011: implement AdvanceTurn domain logic (pure function, events, invariants, 8 acceptance tests)

packages/domain/src/events.ts

@@ -0,0 +1,15 @@
+import type { CombatantId } from "./types.js";
+
+export interface TurnAdvanced {
+	readonly type: "TurnAdvanced";
+	readonly previousCombatantId: CombatantId;
+	readonly newCombatantId: CombatantId;
+	readonly roundNumber: number;
+}
+
+export interface RoundAdvanced {
+	readonly type: "RoundAdvanced";
+	readonly newRoundNumber: number;
+}
+
+export type DomainEvent = TurnAdvanced | RoundAdvanced;