feat: add StateManager.dump() and expose window.__sm for debugging

- StateManager.dump(): console.table formatted dump of variables, flags, history
- window.__sm: exposes engine.stateManager in dev mode for console inspection

src/composables/useGameEngine.ts

@@ -9,6 +9,10 @@ export function useGameEngine(videoEls: () => [HTMLVideoElement | null, HTMLVide
   const saveSystem = new SaveSystem()
   const store = useGameStore()
 
+  if (import.meta.env.DEV) {
+    ;(window as any).__sm = engine.stateManager
+  }
+
   async function loadGame(dataUrl: string) {
     const resp = await fetch(dataUrl)
     const data: GameData = await resp.json()