Robot descriptions v2.16.1

Illustrated color guide

The color guide now includes native rendered comparisons with matching JSON
settings for three independent examples:

• Blue robot/MSG motors.
• Teal MSG Soft TPU inserts, dark blue holders and orange SSG48 Solid jaws.
• A graphite PAR6 cover with teal badge artwork.

All eight URDF/MuJoCo downloads include the updated guide, its images and a
render manifest. Package and product READMEs link to the illustrated guide.

The optional tools/render_color_examples.py renderer uses temporary model
copies and preserves the active palette, runtime models and checked badge
texture. Ordinary headless builds reuse the committed illustrations.

Default colors, model geometry, collisions, kinematics, dynamics, controls and
cameras remain unchanged. Model/assets/documentation licensing stays CC BY 4.0;
support code stays Apache-2.0.