SceneManager.ts

import type { Container } from 'pixi.js';
import type { Game } from './Game';
import { Scene, type SceneClass } from './Scene';

/**
 * Owns the currently-active Scene and provides instant scene transitions.
 *
 * Lifecycle on switch():
 *   1. previous.exit()      — scene cleans up listeners, physics bodies, etc.
 *   2. previous removed and destroyed (children too)
 *   3. new scene constructed and added to root
 *   4. await new.enter(data)
 *   5. new.resize(w, h)     — gives the scene its starting size before first frame
 */
export class SceneManager {
  private current?: Scene;

  constructor(
    private game: Game,
    private root: Container,