Next.js 16.4: Cache Components now recommended and default

Next.js 16.4 makes Cache Components the recommended approach, now enabled by default for new projects created with create-next-app. This model lets you declare cache behavior at the component level, with APIs to control static or dynamic rendering and fine-tune prefetching. The release also brings agent tooling for migration, Turbopack optimizations (cache size, HMR, smaller bundles), support for React 19.3, and several experimental features for build and development.