feat: new OBJ files + chaos architecture scene via MCP

New OBJ files:
- pyramid.obj: 4-sided pyramid with CCW winding
- diamond.obj: octahedron (8 faces, CCW)
- torus.obj: donut shape (24x16 segments)
- cone.obj: 24-sector cone with bottom cap

Scene created via MCP (spawn_model with physics):
- 28 sphere pyramid (7 layers, physics)
- 30 falling diamonds (physics)
- 8 floating torus rings (no physics, decorative)
- 4 pyramid decorations (static)
- 4 cone pillars (static)

Content/pyramid.obj

@@ -0,0 +1,11 @@
+# Pyramid
+v 0 0.5 0
+v -0.5 -0.5 -0.5
+v 0.5 -0.5 -0.5
+v 0.5 -0.5 0.5
+v -0.5 -0.5 0.5
+f 2 4 3
+f 1 3 4
+f 1 4 5
+f 1 5 2
+f 2 5 4