refactor: update eslint to flat config for all projects

[matejchalk]

Updated everything to do with ESLint and fixed related issues.

• Updated ESLint, plugins and shared config to latest version.
• Updated all projects to flat config format.
• All ESLint configs are in ESM, except for the Nx plugin which enforces CommonJS (solved with --experimental-require-module).
• Fix all lint problems from new config and removed unused disable comments.
  • Most changes are from unicorn/import-style, which started enforcing default imports from node:path (e.g. path.join instead of plain join).
    • Nx plugin has to use import * as path from 'node:path' because it's in CommonJS.
• Updated ESLint plugin's integration test fixtures to new format.
• Fixed a bug which was uncovered in new version regarding how ESLint config resolves default options for the new format (caused mismatched audit slugs because of options hash).

[github-actions]

Code PushUp

🤨 Code PushUp report has both improvements and regressions – compared target commit 13a38d6 with source commit cec4a73.

🕵️ See full comparison in Code PushUp portal 🔍

🏷️ Categories

🏷️ Category	⭐ Previous score	⭐ Current score	🔄 Score change
Updates	🟡 75	🟡 80
Performance	🟡 50	🟡 55
Code coverage	🟢 91	🟢 91
Security	🟡 81	🟡 81	–
Accessibility	🟢 91	🟢 91	–
Best Practices	🟢 100	🟢 100	–
SEO	🟡 61	🟡 61	–
Bug prevention	🟢 100	🟢 100	–
Code style	🟢 100	🟢 100	–

👍 2 groups improved, 👎 1 group regressed, 👍 7 audits improved, 👎 3 audits regressed, 12 audits changed without impacting score

🗃️ Groups

🔌 Plugin	🗃️ Group	⭐ Previous score	⭐ Current score	🔄 Score change
JS Packages	NPM outdated dependencies	🟡 75	🟡 80
Lighthouse	Performance	🟡 50	🟡 55
Code coverage	Code coverage metrics	🟢 91	🟢 91

14 other groups are unchanged.

🛡️ Audits

🔌 Plugin	🛡️ Audit	📏 Previous value	📏 Current value	🔄 Value change
Lighthouse	Speed Index	🟥 7.3 s	🟨 5.5 s
JS Packages	Outdated NPM dev dependencies.	🟨 52 outdated package versions (32 major, 15 minor, 5 patch)	🟨 41 outdated package versions (24 major, 11 minor, 6 patch)
Lighthouse	Largest Contentful Paint	🟨 3.4 s	🟨 3.1 s
Lighthouse	Time to Interactive	🟥 16.0 s	🟥 12.7 s
JS Packages	Outdated NPM prod dependencies.	🟨 11 outdated package versions (5 major, 5 minor, 1 patch)	🟨 11 outdated package versions (4 major, 6 minor, 1 patch)
Lighthouse	First Contentful Paint	🟨 2.8 s	🟨 2.9 s
Lighthouse	Total Blocking Time	🟥 7,230 ms	🟥 3,710 ms
Code coverage	Line coverage	🟩 91.1 %	🟩 90.9 %
Code coverage	Function coverage	🟩 93.3 %	🟩 93.1 %
Code coverage	Branch coverage	🟨 85.7 %	🟨 85.7 %
Lighthouse	Minimizes main-thread work	🟥 20.3 s	🟥 14.2 s
Lighthouse	Metrics	🟩 100%	🟩 100%
Lighthouse	JavaScript execution time	🟥 9.0 s	🟥 6.8 s
Lighthouse	Max Potential First Input Delay	🟥 2,700 ms	🟥 1,370 ms
Lighthouse	Eliminate render-blocking resources	🟥 Potential savings of 520 ms	🟥 Potential savings of 1,270 ms
Lighthouse	Uses efficient cache policy on static assets	🟨 28 resources found	🟨 28 resources found
Lighthouse	Avoids enormous network payloads	🟩 Total size was 1,817 KiB	🟩 Total size was 1,817 KiB
Lighthouse	Initial server response time was short	🟩 Root document took 500 ms	🟩 Root document took 440 ms
Lighthouse	Server Backend Latencies	🟩 120 ms	🟩 110 ms
Lighthouse	Reduce unused CSS	🟥 Potential savings of 67 KiB	🟥 Potential savings of 67 KiB
Lighthouse	Network Round Trip Times	🟩 10 ms	🟩 20 ms
Lighthouse	Avoids an excessive DOM size	🟥 2,163 elements	🟥 2,162 elements

438 other audits are unchanged.