chore: upgrade ESLint to v9 and standardize configuration across monorepo #423
Description
Problem
The current ESLint setup is fragmented and outdated:
- Root project uses ESLint
v7.x - Shared config uses
v8.x - Individual packages use mixed versions
- ESLint v9 is now available with significant performance improvements and the new Flat Config system
Description
Standardize linting across the entire monorepo by migrating to ESLint v9.
Migrate all .eslintrc.* files to the new eslint.config.js (Flat Config) format