Fix broken URLs in tool definitions

[mre]

This PR fixes the broken URLs reported in the link checker by either updating them to working alternatives or marking the tools as deprecated.

Changes Made

Updated URLs (6 tools)

• linter-for-dart.yml: Changed homepage from broken GitHub Pages to GitHub repository
• fsharplint.yml: Changed homepage from broken GitHub Pages to GitHub repository
• statix.yml: Changed homepage from unreachable git.peppe.rs to GitHub repository
• cpplint.yml: Updated source and homepage to the current cpplint repository
• specificity-graph.yml: Changed homepage from broken personal website to GitHub repository
• twiggy.yml: Changed homepage from broken GitHub Pages to GitHub repository

Marked as Deprecated (6 tools)

• bugprove.yml: Domain unreachable (certificate/network errors)
• steady.yml: GitHub Pages site not found (404)
• hasmysecretleaked.yml: Gateway timeout (504)
• betterscan.yml: Website unreachable and GitHub repository archived
• kubeval.yml: Domain unreachable (certificate errors)
• scrutinizer.yml: Service unavailable (503)

Link Checker Errors Fixed

This addresses all the broken links mentioned in the GitHub Actions error:

• [ERROR] https://bugprove.com/ ✅ Deprecated
• [404] https://dart-lang.github.io/linter ✅ Updated to GitHub repo
• [404] https://eclipse.github.io/steady/ ✅ Deprecated
• [404] https://fsprojects.github.io/FSharpLint ✅ Updated to GitHub repo
• [TIMEOUT] https://git.peppe.rs/languages/statix/about/ ✅ Updated to GitHub repo
• [504] https://gitguardian.com/hasmysecretleaked ✅ Deprecated
• [404] https://github.com/google/styleguide/tree/gh-pages/cpplint ✅ Updated to current repo
• [404] https://github.com/tcosolutions/betterscan-ce ✅ Deprecated
• [404] https://jonassebastianohlsson.com/specificity-graph ✅ Updated to GitHub repo
• [ERROR] https://kubeval.instrumenta.dev/ ✅ Deprecated
• [404] https://rustwasm.github.io/twiggy ✅ Updated to GitHub repo
• [503] https://scrutinizer-ci.com/ ✅ Deprecated
• [ERROR] https://www.betterscan.io/ ✅ Deprecated

All changes preserve the original functionality while providing working URLs or properly marking tools as deprecated using the deprecated: true flag as shown in the existing codebase.