Add tap-controlled incremental space-knight game

Auto-flying knight, crystal zones, pirate/boss combat, shop upgrades,
falling/golden asteroids, particle juice, droid evolution, and a
supernova prestige cutscene, per the design spec.

Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01D5SuZW1XGCkahPX7cHMoRP

src/hooks/useGameEngine.ts

@@ -0,0 +1,24 @@
+import { useEffect, useRef, useState, type RefObject } from 'react';
+import { GameEngine } from '../game/GameEngine';
+import type { GameSnapshot } from '../game/types';
+
+export function useGameEngine(canvasRef: RefObject<HTMLCanvasElement | null>) {
+  const engineRef = useRef<GameEngine | null>(null);
+  const [snapshot, setSnapshot] = useState<GameSnapshot | null>(null);
+
+  useEffect(() => {
+    const canvas = canvasRef.current;
+    if (!canvas) return;
+    const engine = new GameEngine(canvas);
+    engineRef.current = engine;
+    const unsubscribe = engine.subscribe(setSnapshot);
+    engine.start();
+    return () => {
+      unsubscribe();
+      engine.stop();
+      engineRef.current = null;
+    };
+  }, [canvasRef]);
+
+  return { engine: engineRef, snapshot };
+}