reduce-draw-callslisted

# Cut draw calls, ranked by cost Work the ladder in order and stop at the first rung that clears the budget. Each rung trades away less flexibility than the next; skipping straight to a custom renderer or hand-written mesh merge costs more engineering time than the draw calls it saves. ## Measure first Read `app.stats.drawCalls.total` (or the `forward`/`depth`/`shadow` breakdown) before changing anything, or drop in `MiniStats` for a live overlay. Every rung below is proved against this number, not against intuition about what "looks expensive." Draw count alone does not identify the bottleneck. Test sensitivity to pixel cost by halving the effective pixel ratio (`Math.min(graphicsDevice.maxPixelRatio, window.devicePixelRatio)`) and calling `app.resizeCanvas()`. Verify the backbuffer shrank and compare frame times at the same scene state. If frame time improves materially, prioritize resolution, multisampling and per-pixel shader cost. Otherwise profile CPU and GPU work before choosing a rung; restore the original ratio after the test. ## Rung 1: stop drawing invisible things An element at opacity 0 still submits a draw call — its mesh instance exists and is still in a layer, so the GPU processes it every frame for no visible result. Toggle `enabled` on the entity to actually skip it. Check every element that is ever fully transparent, not only the ones on screen when you're profiling — this rung is easy to skip precisely because nothing looks wrong. ## Rung 2: `BatchM