chore(deps): group React dependency updates

[erseco]

Summary

• group react and react-dom Dependabot version updates
• keep the grouping scoped to the npm ecosystem

Why

Dependabot opened #92 and #94 as separate updates. Each PR fails during npm install because react and react-dom require compatible versions and only one package is upgraded at a time.

Impact

Future Dependabot version updates for these two packages will be proposed in the same pull request.

Validation

• parsed the updated .github/dependabot.yml successfully
• verified that the react group is nested under the npm update configuration
• verified the exact package patterns: react and react-dom

[github-actions]

Test in WordPress Playground

Test the plugin with the code from this branch:

ℹ️ The eXeLearning editor is fetched from the shared release and unpacked into the plugin when the playground boots, so the first load may take a few extra seconds. ELP upload, shortcode, Gutenberg block and preview work normally.

[codecov-commenter]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 96.87%. Comparing base (93cd977) to head (a56be00).
⚠️ Report is 1 commits behind head on main.

Additional details and impacted files

@@            Coverage Diff            @@
##               main      #97   +/-   ##
=========================================
  Coverage     96.87%   96.87%           
  Complexity      864      864           
=========================================
  Files            39       39           
  Lines          4323     4323           
=========================================
  Hits           4188     4188           
  Misses          135      135           

Flag	Coverage Δ
javascript	95.70% <ø> (ø)
php	97.25% <ø> (ø)

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