* feat: prioritize pruning of old SHA when pulling updated tags
When pulling a new version of a tagged image (e.g., ghcr.io/cirruslabs/macos-runner:sonoma),
set the access date of the previous SHA to epoch time (1970-01-01). This ensures that the
old SHA will be prioritized for pruning, even if it was accessed more recently than other
cached images.
This helps manage disk space more efficiently by automatically cleaning up superseded
versions of frequently-updated tagged images.
🤖 Generated with [Claude Code](https://claude.ai/code)
Co-Authored-By: Claude <noreply@anthropic.com>
* format
* Review comments
---------
Co-authored-by: Claude <noreply@anthropic.com>