Fix eslint config

[ryan-pratt]

@vue/eslint-config-prettier v10.0.0 removed support for the legacy config format that we were using with compat.extends([...] "@vue/prettier"). Replaced that with the new flat format.

Also:

• removed the vue stuff from js-common's config
• bumped ace-diff ecmaVersion so it matches everything else
• cleaned up some ugliness that was generated by the eslint flat config migration tool

[sonarqubecloud]

Quality Gate passed

Issues
0 New issues
0 Accepted issues

Measures
0 Security Hotspots
0.0% Coverage on New Code
87.6% Duplication on New Code

See analysis details on SonarQube Cloud

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 79.58%. Comparing base (34889a4) to head (9216eb3).
Report is 5 commits behind head on main.

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #1792      +/-   ##
==========================================
+ Coverage   79.56%   79.58%   +0.01%     
==========================================
  Files         517      517              
  Lines       40737    40737              
==========================================
+ Hits        32412    32420       +8     
+ Misses       8325     8317       -8     

Flag	Coverage Δ
python	84.30% <ø> (+0.05%)	⬆️
ruby-api	48.64% <ø> (ø)
ruby-backend	82.61% <ø> (ø)

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