HTML report generation

[FumingPower3925]

Problem

Results are only available as structured data or plain text. No visual reporting for sharing or analysis.

Solution

Generate interactive HTML reports with:

• Latency histogram (HDR histogram visualization)
• Throughput timeline (requests/sec over time, requires timeseries data)
• Percentile comparison chart (p50, p90, p99, p99.9)
• Summary table (total requests, errors, duration, avg/min/max latency)
• Embedded — single self-contained HTML file (no external dependencies)

Add Config.ReportPath string or Result.WriteHTML(w io.Writer) error.

Acceptance Criteria

• HTML report generated from Result
• Charts render correctly
• Single self-contained HTML file
• CLI flag: -report report.html

Future

This is a post-v1.0.0 feature.