Bump eslint v8 to v9 and migrate legacy config format to new format

[consideRatio]

With eslint v9, we need a new format for the eslint config file we have.

eslint...................................................................Failed
- hook id: eslint
- exit code: 2

Oops! Something went wrong! :(

ESLint: 9.21.0

ESLint couldn't find an eslint.config.(js|mjs|cjs) file.

From ESLint v9.0.0, the default configuration file is now eslint.config.js.
If you are using a .eslintrc.* file, please follow the migration guide
to update your configuration file to the new format:

https://eslint.org/docs/latest/use/configure/migration-guide

If you still have problems after following the migration guide, please stop by
https://eslint.org/chat/help to chat with the team.

[Neoxs]

@consideRatio

🚀 Just completed an ESLint v9 migration, and wow… what a ride! 😵‍💫

I ran into breaking changes, weird errors, and unexpected surprises—but I documented everything so you don’t have to suffer the same way.

If you’re upgrading (or still hesitating), this guide might save you some headaches:
📖 neoxs.me/blog/migration-to-eslint-v9

[consideRatio]

Thank you for sharing @Neoxs!!