Auto-format code to comply with Black's 100-character line length limit.
Fixed files:
- tests/test_options.py
- tests/test_layers.py
- tests/test_scatter_renderer.py
- glplot/utils/shaders.py
- glplot/utils/preview.py
- glplot/engine.py
- glplot/pyplot.py

All files now pass Black formatting checks.

Co-Authored-By: Claude Haiku 4.5 <noreply@anthropic.com>