Add HTML report exporter with charts

[aviralgarg05]

Summary

Add an HTML report exporter that generates a standalone, styled HTML file with interactive charts.

Tasks

• Create SuiteResult.to_html(path) method.
• Include summary stats, per-scenario tables, and metric charts (use inline JS/CSS or Chart.js CDN).
• Make it self-contained (single HTML file).
• Add tests verifying HTML structure.

Acceptance criteria

• result.to_html("report.html") produces valid HTML.
• Report renders correctly in modern browsers.
• Charts display metric trends if multiple runs exist.

[anshiky73-svg]

Hi, I’d like to work on this issue. Please assign it to me
@aviralgarg05