ESLint config for Chart.js projects

Shareable ESLint configuration from the Chart.js team. v0.3.0 switches indent from tabs to 2 spaces and enables ES6 features. Release cadence is low; used primarily for maintaining Chart.js itself. Differentiator: official config that matches Chart.js coding style, including spacing, brace style, and ES6 enforcement. Supports extending in ESLint config files.