[CMGS]

Gives the repo the branch and release model of cocoonstack/cloud-hypervisor.

• build.yaml (reusable): both arches through the builder image, which runs --self-test; su1000; patched scrcpy-server; assembles dist with build-info.json and SHA256SUMS.
• ci.yaml: runs build.yaml on every pull request and on pushes to dev; publishes nothing.
• dev-release.yaml: pushes to dev update the rolling dev prerelease (Branch / Commit / Workflow Run body) and the ghcr :dev image.
• release.yaml: pushing a tag dev-<9-char sha> publishes a non-prerelease with the same assets once (overwrite_files: false) and the ghcr image tagged with it.
• Replaces the old master workflow. Actions are pinned to exact version tags.

Downstream images should pin a dev-<sha9> release and its SHA256SUMS, not the moving dev release, whose assets are rebuilt on every merge.

[CMGS]

Superseded by #11: the master model, no separate dev branch.