Enhance redirect detection: add support for meta refresh and JavaScript support

[qpst4]

Enhance Redirect Detection with Meta Refresh and JavaScript Support

Description

This PR adds enhanced redirect detection capabilities to handle complex redirect scenarios that return HTTP 200 status code with hidden redirects in the HTML content.

Features Added

• ✅ HTML Meta Refresh Detection: Now detects and follows <meta http-equiv="refresh"> tags
• ✅ Advanced JavaScript Redirect Detection: Handles multiple JavaScript redirect patterns including:
  • Direct string assignments: window.location = "url"
  • Variable references: window.location = varName (automatically resolves variable definitions)
  • URL-encoded strings with decoding support
  • decodeURIComponent() wrapped URLs
• ✅ URL Decoding: Properly handles URL-encoded characters using URLDecoder
• ✅ Improved URL Resolution: Better handling of relative URLs to absolute URLs

Problem Solved

Previously, URLCheck could not detect redirects that returned HTTP 200 but contained redirect instructions in the HTML body. This is common with URL shorteners and redirect services.

Example Case

URLs like https://kurl06.cn/t8RnP3 that respond with:

<meta http-equiv="refresh" content="0.1;url=https://coupon.m.jd.com/...">with URL decoding

[TrianguloY]

Hi. I apologize for not saying anything until now, but I have important personal matters to attend, and even though I though they wouldn't take long, it is taking way longer than I expected, I'm sorry.
I noted the pr though, and I do want to review it when I'm back to normal, but I can't say when.

Feel free to ping me if I haven't said anything in a month. Thanks.