Modernize passive scanner report UX with Tailwind wrapper

[viyatb]

Summary

Modernizes passive scanner UX while keeping the upstream scanner engine available.

Changes

1. Header cleanup

• Reduced GitHub button crowding (whitespace-nowrap, shorter label).

2. Scanner copy improvement

• Replaced "This Jekyll page..." wording with a clear explanation of what passive scanning is for.

3. Modern report UX

• Added Tailwind report page: /passive-scanner/report/.
• Parses #q= target and presents a cleaner report shell.
• Embeds legacy report engine in an iframe for compatibility.
• Provides quick actions (Open classic report, Scan another URL).

4. Route behavior

• online-passive-scanner/report.html now redirects to modern /passive-scanner/report/.
• Preserved old report implementation as online-passive-scanner/report-legacy.html.

5. CI coverage

• Added link-check coverage for new report route and legacy file in both workflows.

Why

Users currently land on a legacy jQuery-heavy report page. This keeps scanner capability but upgrades the default UX to match the modern site design.