feat(highcharts): implement scatter-basic

[claude]

Summary

Implements scatter-basic for highcharts library.

Parent Issue: #207
Sub-Issue: #442
Base Branch: plot/scatter-basic
Attempt: 1/3

Implementation

• plots/highcharts/scatter/scatter-basic/default.py

Details

• Basic scatter plot with 100 random data points showing positive correlation
• Uses Python Blue (#306998) color for data points (from style guide)
• X and Y axis labels with readable font sizes
• Grid lines at 10% opacity for subtle visual guidance
• Chart dimensions: exactly 4800 x 2700 px (16:9 aspect ratio)
• Uses PIL to crop screenshot to exact dimensions required
• Headless Chrome + Selenium for PNG export
• Inline Highcharts JS embedding (required for headless Chrome)

[github-actions]

✅ Plot Tests Passed

Python 3.13 (required): passed

Compatibility:

Note: Only Python 3.13 is required to pass. Python 3.12 is tested for compatibility.