fix(LinkDialog): Fix anchor regex to handle hyphens in URL fragments

[tvdeyen]

What is this pull request for?

The fragment-stripping regex used \w+ which only matches word characters and fails on hyphens, causing double hash anchors (e.g. /page#my-section#new-section). The new ANCHOR_REGEX covers all RFC 3986 unreserved characters ([\w.~-]).

Checklist

• I have followed Pull Request guidelines
• I have added a detailed description into each commit message
• I have added tests to cover this change

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 97.46%. Comparing base (3d92382) to head (f6467a9).
⚠️ Report is 2 commits behind head on main.

Additional details and impacted files

@@           Coverage Diff           @@
##             main    #3683   +/-   ##
=======================================
  Coverage   97.46%   97.46%           
=======================================
  Files         314      314           
  Lines        8288     8288           
=======================================
  Hits         8078     8078           
  Misses        210      210           

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[alchemycms-bot]

💚 All backports created successfully

Status	Branch	Result
✅	7.4-stable
✅	8.0-stable
✅	8.1-stable

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