Cloudflare deploy: one app, several environments #468

What

On direct Cloudflare deploys, one app directory can deploy to only one environment.

The deploy reference marks named environments "Unavailable; use the top-level cloudflare config", and --project as unsupported (CLI: deploy).
The Cloudflare guide says "Named environments need separate Void project configs" (Cloudflare). But void.config.ts sits at the project root, void deploy has no flag to choose a different config, and no page explains how to do it.

Today we deploy one app directory to development, staging and production Workers, each with its own resources.

Done when

One app directory deploys to at least two environments, each with its own Worker and resources, chosen at deploy time.