docker: add combined static package

[crazy-max]

fixes #315

This adds a docker static package that produces the combined Engine, CLI, and runtime archive needed to replace the legacy static artifacts. It keeps the package on the existing matrix model, builds Linux archives with docker, dockerd, containerd, ctr, containerd-shim-runc-v2, runc, docker-init, and docker-proxy, and builds Windows archives with docker.exe, dockerd.exe, containerd.exe, ctr.exe, and containerd-shim-runhcs-v1.exe.

After this lands, the next step is to move the release flow over to these docker/packaging artifacts and then deprecate docker-ce-packaging once it no longer owns the Engine and CLI static package path.

[crazy-max]

https://github.com/docker/packaging/actions/runs/31806641319/job/94789797279#step:6:11

[4.0K]  ./bin/pkg/docker
└── [4.0K]  static
    ├── [4.0K]  linux_amd64
    │   ├── [ 94K]  provenance.json
    │   ├── [ 19M]  sbom-build-pkg.spdx.json
    │   ├── [1.3K]  sbom.spdx.json
    │   └── [4.0K]  static
    │       └── [4.0K]  linux
    │           └── [4.0K]  amd64
    │               └── [ 82M]  docker-0.0.0-20260814110427-7e1098f.tgz
    ├── [4.0K]  linux_arm64
    │   ├── [ 94K]  provenance.json
    │   ├── [ 19M]  sbom-build-pkg.spdx.json
    │   ├── [1.3K]  sbom.spdx.json
    │   └── [4.0K]  static
    │       └── [4.0K]  linux
    │           └── [4.0K]  arm64
    │               └── [ 74M]  docker-0.0.0-20260814110427-7e1098f.tgz
    ├── [4.0K]  linux_arm_v6
    │   ├── [ 94K]  provenance.json
    │   ├── [ 22M]  sbom-build-pkg.spdx.json
    │   ├── [1.3K]  sbom.spdx.json
    │   └── [4.0K]  static
    │       └── [4.0K]  linux
    │           └── [4.0K]  arm
    │               └── [4.0K]  v6
    │                   └── [ 76M]  docker-0.0.0-20260814110427-7e1098f.tgz
    ├── [4.0K]  linux_arm_v7
    │   ├── [ 94K]  provenance.json
    │   ├── [ 22M]  sbom-build-pkg.spdx.json
    │   ├── [1.3K]  sbom.spdx.json
    │   └── [4.0K]  static
    │       └── [4.0K]  linux
    │           └── [4.0K]  arm
    │               └── [4.0K]  v7
    │                   └── [ 76M]  docker-0.0.0-20260814110427-7e1098f.tgz
    ├── [4.0K]  linux_ppc64le
    │   ├── [ 94K]  provenance.json
    │   ├── [ 22M]  sbom-build-pkg.spdx.json
    │   ├── [1.3K]  sbom.spdx.json
    │   └── [4.0K]  static
    │       └── [4.0K]  linux
    │           └── [4.0K]  ppc64le
    │               └── [ 75M]  docker-0.0.0-20260814110427-7e1098f.tgz
    ├── [4.0K]  linux_s390x
    │   ├── [ 94K]  provenance.json
    │   ├── [ 22M]  sbom-build-pkg.spdx.json
    │   ├── [1.3K]  sbom.spdx.json
    │   └── [4.0K]  static
    │       └── [4.0K]  linux
    │           └── [4.0K]  s390x
    │               └── [ 80M]  docker-0.0.0-20260814110427-7e1098f.tgz
    ├── [4.0K]  windows_amd64
    │   ├── [ 94K]  provenance.json
    │   ├── [ 19M]  sbom-build-pkg.spdx.json
    │   ├── [1.3K]  sbom.spdx.json
    │   └── [4.0K]  static
    │       └── [4.0K]  windows
    │           └── [4.0K]  amd64
    │               └── [ 77M]  docker-0.0.0-20260814110427-7e1098f.zip
    └── [4.0K]  windows_arm64
        ├── [ 94K]  provenance.json
        ├── [ 16M]  sbom-build-pkg.spdx.json
        ├── [1.3K]  sbom.spdx.json
        └── [4.0K]  static
            └── [4.0K]  windows
                └── [4.0K]  arm64
                    └── [ 69M]  docker-0.0.0-20260814110427-7e1098f.zip

[tianon]

Does this mean we finally have hope for the possibility of checksums on these static artifacts? 😅