docs: fix broken star history chart by using a new provider

[Mubelotix]

The star history chart in the README is currently broken because GitHub now restricts the stargazer API to repository owners only. This change points the image and link to star-history.dera.page, a token-free alternative that requires no extra configuration or API tokens.

[boring-cyborg]

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[Copilot]

Pull request overview

This PR updates the README’s “Star History” badge/link to use an alternative star-history chart provider, addressing the currently broken chart caused by GitHub stargazer API access restrictions.

Changes:

• Switched the Star History SVG image URL to https://star-history.dera.page/svg?...
• Updated the Star History link target to https://star-history.dera.page/#...

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[DaanHoogland]

lgtm (readme text only)

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 19.64%. Comparing base (cced071) to head (05d027d).

Additional details and impacted files

@@             Coverage Diff              @@
##               main   #13844      +/-   ##
============================================
- Coverage     19.64%   19.64%   -0.01%     
  Complexity    19786    19786              
============================================
  Files          6368     6368              
  Lines        574889   574889              
  Branches      70353    70353              
============================================
- Hits         112957   112951       -6     
- Misses       449660   449666       +6     
  Partials      12272    12272              

Flag	Coverage Δ
uitests	3.41% <ø> (ø)
unittests	20.92% <ø> (-0.01%)	⬇️

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