Replace addons with conventional handles

Provide the single-loadout Scene API, SAB-backed meshes, cameras, materials, lights, workers, post effects, and tutorial playgrounds. Batch matching row growth so active GPU loadouts refresh once.

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

addons/handles/src/PostProcesses/Edges.ts

@@ -0,0 +1,6 @@
+import { PostProcess } from "./PostProcess";
+import type { Scene } from "../Scene";
+
+export class Edges extends PostProcess {
+  constructor(scene: Scene, options: { amount?: number; enabled?: boolean } = {}) { super(scene, "edges", options); }
+}