Add IDE selector for file links in HTML reports to Development

[mrtwebdesign]

Summary

• Adds IDE selector UI with buttons for VS Code, Cursor, Augment, and File protocols
• Positions selector just above Findings section for clear association with file links
• Stores user preference in localStorage for persistence across reports
• Clicking a file link opens directly in the selected IDE at the correct line number

Test plan

• Generate an HTML report with json-to-html.py
• Verify IDE selector appears above Findings section
• Click each IDE button and verify links update (inspect href)
• Click a file link with VS Code/Cursor selected to verify it opens in IDE
• Refresh page and verify preference is remembered

Closes #65

🤖 Generated with Claude Code

[mrtwebdesign]

I tested with VS Code and Cursor. You will have to approve the browser opening the first link, but after that it just works.
I did not test with Augment as I don't have it installed. But the link did nothing when set to Augment for me which is the intended failure mode.

[mrtwebdesign]

closes #65