feat(highcharts): implement scatter-basic

[claude]

Summary

Implements scatter-basic for highcharts library.

Parent Issue: #207
Sub-Issue: #275
Base Branch: plot/scatter-basic
Attempt: 1/3

Implementation

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

Details

• Uses highcharts-core Python library with Selenium for PNG export
• Follows pyplots style guide with Python Blue (#306998) color
• Target image dimensions: 4800 × 2700 px
• Generates 100 random data points with clear correlation pattern
• Clean axis labels and title with appropriate font sizes

[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.