Add draw_text and draw_overlay methods to Renderer

[Shivam-Bhardwaj]

Summary

• Add draw_text() method to render 2D text at (x, y) coordinates with RGB color support
• Add draw_overlay() method to render text at grid positions (top-left, bottom-right, etc.)
• Exposes mjr_text and mjr_overlay functionality in the Python Renderer utility

Closes #1864

Test plan

• Added unit tests for draw_text()
• Added unit tests for draw_overlay()
• Added test verifying text queue is cleared after render
• Added test verifying text is not drawn in depth mode
• Ran pyink and isort for style compliance

Example usage

with mujoco.Renderer(model, 480, 640) as renderer:
    renderer.update_scene(data, camera)
    
    # Draw colored text at position
    renderer.draw_text('Hello', x=0.5, y=0.9, rgb=(1.0, 0.0, 0.0))
    
    # Draw overlay in corner
    renderer.draw_overlay('Frame: 100', 'FPS: 60', 
                          position=mujoco.mjtGridPos.mjGRID_TOPLEFT)
    
    pixels = renderer.render()

🤖 Generated with Claude Code

[google-cla]

Thanks for your pull request! It looks like this may be your first contribution to a Google open source project. Before we can look at your pull request, you'll need to sign a Contributor License Agreement (CLA).

View this failed invocation of the CLA check for more information.

For the most up to date status, view the checks section at the bottom of the pull request.