Add interactive tutorial playgrounds

Embed editable split-view examples throughout the guide, restore the full LFS-backed Sponza demo, batch glTF hydration, honor hierarchical transforms, and report transformed BVH picks with a live FPS counter.

Amp-Thread-ID: https://ampcode.com/threads/T-01a01380-b478-77d0-84a0-102880a5c5ae
Co-authored-by: Heaust Azure <heaust.azure@gmail.com>

docs/guide/scene-and-sab.md

@@ -18,6 +18,8 @@ canvas.addEventListener("pointermove", (event) => {
 
 The pointer handler sends no messages. The typed-array view points directly into the arena shared with the render worker. The camera helpers use this same pattern; see [Cameras and controls](/guide/cameras).
 
+<Playground example="sab" />
+
 ## Add an application-specific row
 
 ```ts
@@ -42,3 +44,7 @@ info[4] = 0; // resume rendering
 ```
 
 Use messages for rare control changes (`setFps`, graph updates, allocation); use SAB writes for existing hot state.
+
+<script setup>
+import Playground from "../.vitepress/Playground.vue";
+</script>