Backends on Vercel: Python, containers, and Daemons

Introduces Vercel Daemons in Public Beta for continuously running background workers, supporting pull-based workloads and maintaining capacity on Fluid compute. Expands container support in Vercel Functions to deploy applications in any language packaged with OS libraries and executables, leveraging Active CPU pricing and integrating with Vercel's platform services. Python backend support is now generally available, with SDKs for Vercel products.