kylejrp/assetgraph-avif-repro

This project is a minimal reproduction of an issue in assetgraph where it throws warnings when processing HTML with `<picture>` elements containing AVIF image sources. It demonstrates that assetgraph doesn't recognize `.avif` files as a known image type, and includes a proposed fix to add AVIF support by creating a new `Avif.js` asset class. The project is intended for assetgraph developers or contributors working on improving image format support.