feat: implement version check in CI, update cleanup process for old MinIO resources, and bump version to 0.2.7

[ronibhakta1]

This pull request focuses on improving the safety and clarity of the S3-to-Garage migration process, adds automation to enforce version bumping for deployable changes, and updates documentation to guide users through post-migration cleanup. The migration script is now more robust, always using a temporary container for data migration and clarifying container/volume/image removal steps. Additionally, the VERSION file is bumped to reflect these changes.

Migration and Cleanup Improvements:

• The S3-to-Garage migration script (025_migrate_s3_to_garage.sh) is updated to always stop the old lenny_s3 container and use a dedicated temporary container (with a hyphenated alias to avoid MinIO hostname issues) for data migration, preventing race conditions and ensuring safe, idempotent operation. [1] [2] [3]
• The Makefile's cleanup-old-s3 target now also removes the old MinIO Docker images in addition to the container and volume, and the corresponding echo message is updated.
• Documentation is expanded to instruct users on how to clean up old MinIO resources after migration, clarifying what is removed and when. [1] [2]

Automation and Versioning:

• A new version-check job is added to the CI workflow (ci.yml) to ensure that any PR changing deployable code or configuration also bumps the VERSION file, helping maintain update pipeline integrity.
• The VERSION file is incremented from 0.2.6 to 0.2.7 to reflect these changes.