feat: add support for Scalar UI

[maks-oleksyuk]

Description

Adds support for https://scalar.com as an alternative API documentation UI renderer, alongside the existing SwaggerUI, Redocly, and Stoplight Elements options.

What's included:

• New scalar renderer constant in Renderer.php
• scalar_config configuration node to pass https://scalar.com/products/api-references/configuration
• Dedicated Twig template (templates/Scalar/index.html.twig) with bundled standalone JS
• New routing file (config/routing/scalar.php) for serving the Scalar UI
• Service definition for the Scalar controller
• Documentation update in docs/configuration_reference.rst

Closes #...

What type of PR is this? (check all applicable)

• Bug Fix
• Feature
• Refactor
• Deprecation
• Breaking Change
• Documentation Update
• CI

Checklist

• I have made corresponding changes to the documentation (docs/)

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 95.60%. Comparing base (e6a9666) to head (92955ac).
⚠️ Report is 3 commits behind head on 5.x.
✅ All tests successful. No failed tests found.

Additional details and impacted files

@@            Coverage Diff             @@
##              5.x    #2711      +/-   ##
==========================================
+ Coverage   95.59%   95.60%   +0.01%     
==========================================
  Files          94       94              
  Lines        3064     3075      +11     
==========================================
+ Hits         2929     2940      +11     
  Misses        135      135              

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[HecFranco]

I’d like to give this PR some visibility because I think it adds real value to the bundle.

Supporting Scalar as an additional API documentation renderer feels like a very useful improvement: it expands the available UI options without replacing the existing ones, includes documentation updates, and the checks/coverage look good from what is shown in the PR. This could make NelmioApiDocBundle more flexible for teams that want a more modern API reference experience. ([GitHub]1)

Even though this is not my PR, I believe it would be great to review and approve it if it aligns with the project direction. It seems like a valuable feature addition for the community. ([GitHub]1)

[DjordyKoert]

Sorry for the late reply!

This looks great, thank you very much! ❤️