Add runtime global state interfaces and default creation function

src/runtime-three/runtime-global-state.ts

@@ -0,0 +1,24 @@
+export interface RuntimeSceneTransitionRecord {
+  fromSceneId: string;
+  fromSceneName: string;
+  toSceneId: string;
+  toSceneName: string;
+  viaExitEntityId: string;
+  targetEntryEntityId: string;
+}
+
+export interface RuntimeGlobalState {
+  flags: Record<string, boolean>;
+  activeMusicCueId: string | null;
+  transitionCount: number;
+  lastSceneTransition: RuntimeSceneTransitionRecord | null;
+}
+
+export function createDefaultRuntimeGlobalState(): RuntimeGlobalState {
+  return {
+    flags: {},
+    activeMusicCueId: null,
+    transitionCount: 0,
+    lastSceneTransition: null
+  };
+}