Add cp command and R2 upload endpoint
Provide a /cp POST endpoint that accepts a file upload and stores
it in the POCKETENV_COPY R2 bucket under a generated UUID. Add a
CLI "copy" command (alias cp) that ties into the sandbox copy flow
with a spinner. Update wrangler.jsonc and generated worker types
to declare the POCKETENV_COPY binding, update apps/cli deps and
bun.lock, and add a GitHub Actions step to deploy the main worker
using bunx wrangler deploy.