ci: tag docker image with short commit sha

[alxdca]

Summary

• Add short Git commit SHA tagging to the Docker image publish workflow.
• Keep existing semver and branch image tags while adding an immutable commit-derived tag.

Why / Context

• Docker images published from releases or branches are currently tagged by semver and branch references.
• Adding the short commit SHA makes it easier to trace a published image back to the exact source revision.