Profiler (web): add "Download HTML report" and "Copy as JSON" buttons

[yakew7]

Summary

The CLI can emit --html and --json, but profiler.html only renders on-screen. Add a "Download report (HTML)" and "Copy results as JSON" action to the results panel.

Why

Lets users save/share an audit without re-running the CLI. Reuses to_html/to_json logic already in faircode/report.py (port to JS).

Tasks

• Port the HTML report template to the browser (or build a Blob download)
• "Copy as JSON" button using the existing result object
• Keep everything client-side (no upload)