The reset CronJob fails with `getaddrinfo EAI_AGAIN registry.npmjs.org`
when cluster DNS is flaky, because the reset stage uses corepack to
download pnpm at runtime instead of having it baked into the image.
This change adds `corepack enable && corepack prepare pnpm@9.15.4 --activate`
to the reset Dockerfile stage so pnpm is pre-installed at build time.
Co-Authored-By: Paperclip <noreply@paperclip.ing>