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/core.md

@@ -42,3 +42,9 @@ values.row(id).set([1, 2, 3, 4]);
 Graph frontends serialize plain data to `(yawn-graph 1 ...)`. Named `after` edges preserve DAG fan-out; Rust sorts passes, detects cycles, culls unused declarations, plans compatible transient lifetimes, and allocates the active loadout.
 
 The `Scene` addon is one such frontend. It is replaceable and has no privileged core API.
+
+<Playground example="core" />
+
+<script setup>
+import Playground from "../.vitepress/Playground.vue";
+</script>