fix(docker): download mc from its GitHub release, MinIO withdrew dl.min.io and its images

[abir-oumghar]

Description

docker/Dockerfile copied the mc client from the quay.io/minio/mc image since #39. MinIO closed its quay.io repositories on 2026-09-22, so the image cannot be rebuilt: the FROM quay.io/minio/mc stage fails with 401. The published quay.io/okdp/okdp-examples:1.2.0 still works.

The signed binaries are still attached to the GitHub releases of the archived minio/mc repository, with their checksums. The Dockerfile goes back to a plain download, from that release instead of dl.min.io, verifies the published sha256 and picks the linux-${TARGETARCH} asset so the image builds on amd64 and arm64. The example scripts are untouched.

Related Issue

Fixes #40

Type of Change

• Bug fix
• New feature
• Documentation update
• Refactor / chore
• Breaking change

How to Test

1. docker build -f docker/Dockerfile -t okdp-examples-test . from the repository root completes (on main it fails at the quay.io stage with 401).
2. docker run --rm --entrypoint sh okdp-examples-test -c 'mc --version; trino --version; python --version' prints mc version RELEASE.2025-08-13T08-35-41Z (commit-id=7394ce0dd2a80935aded936b09fa12cbb3cb8096), Trino CLI 480 and Python 3.12.x.

Done locally on arm64; the CI build covers amd64.

Checklist

• I have tested my changes
• Documentation updated if needed
• If breaking change: migration path described above
• I hereby declare this contribution to be licensed under the Apache License Version 2.0.
• I hereby agree to grant TOSIT a copyright license to use my contributions.

[abir-oumghar]

Merge order: independent of the seaweedfs chain (OKDP/helm-charts-utilities#38, then OKDP/sandbox-dependencies#46), can go any time.