Adds a GitHub Action that builds the Next.js standalone output on
release and attaches architecture-specific tarballs (amd64 + arm64)
as release assets. Downstream projects can download and extract
instead of building from source.
Closes#178
Add GitHub Actions workflow to automatically build and publish Docker
images to ghcr.io on releases. Supports amd64 and arm64 architectures.
Pre-built image available at ghcr.io/root-fr/jmap-webmail.