Interattivo Avatar: a robot whose limbs mirror your tracked body 1:1

Raise your arm and the robot raises its arm. ModelSim gains primitive
meshes (cube/sphere) and renderAvatar(): parts placed by limb matrices
(basis aligned to each bone segment) with the same lighting as the GLB
renderer. interactive.js keeps the mirrored raw landmarks (with depth,
smoothed) and builds the robot every frame: torso sized from the
shoulders, head with accent visor and antenna, articulated arms/legs
with joint spheres, glowing hands, feet. Falls back to the motion mist
when no body is tracked.

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>

src/visualizer.js

@@ -120,8 +120,8 @@ class Visualizer {
     if (e.isInteractive && window.InteractiveSim) {
       if (!this.inter) this.inter = new window.InteractiveSim(gl);
       this.inter.customSource = this.customSource || null;
-      // The model-puppet mode drives the shared 3D renderer.
-      if (e.interactiveMode === 'model' && window.ModelSim) {
+      // The model-puppet and avatar modes drive the shared 3D renderer.
+      if ((e.interactiveMode === 'model' || e.interactiveMode === 'avatar') && window.ModelSim) {
         if (!this.model3d) this.model3d = new window.ModelSim(gl);
         if (this._pendingGlb) { this.model3d.setModel(this._pendingGlb); this._pendingGlb = null; }
         this.inter.modelSim = this.model3d;