chore: adjust viteconfig to remove outdated assets

[susnux]

📝 Summary

CSS assets need to be cleaned if committed.
So adding css/ to the list of directories to clean on build. Also fix some code style issues and remove unneeded dependency.

🏁 Checklist

• Code is properly formatted (npm run lint / npm run stylelint / composer run cs:check)
• Sign-off message is added to all commits
• Tests (unit, integration and/or end-to-end) passing and the changes are covered with tests
• Documentation (README or documentation) has been updated or is not required

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 51.86%. Comparing base (c384831) to head (0dfe99c).
Report is 2 commits behind head on main.

Additional details and impacted files

@@           Coverage Diff           @@
##             main    #7073   +/-   ##
=======================================
  Coverage   51.86%   51.86%           
=======================================
  Files         478      478           
  Lines       40709    40709           
  Branches      993      993           
=======================================
  Hits        21112    21112           
  Misses      19492    19492           
  Partials      105      105           

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[mejo-]

Thanks @susnux!