Quadtree debug drawing broken — renders after renderer flush

[obiot]

The debug panel's quadtree visualization doesn't render correctly because _drawQuadTree() is called in the GAME_AFTER_DRAW event handler, which fires after renderer.flush() in the application draw loop.

The draw sequence is:

1. GAME_BEFORE_DRAW
2. renderer.clear() + stage draw
3. renderer.flush() — batch submitted to GPU
4. GAME_AFTER_DRAW — quadtree draws here, after flush

The quadtree draw calls go into a new batch that never gets flushed (it's cleared on the next frame's renderer.clear()).

Fix

Add video.renderer.flush() after the quadtree drawing in _drawQuadTree(), or move the drawing to before the flush.