feat: add branch name and schema version as layer annotations

[shino]

Want to distinguish non-tagged old images whether it's main or nightly.
Also, adding schema version annotations may help.

• https://github.com/vulsio/vuls-nightly-db/pkgs/container/vuls-nightly-db/809990355
• https://oras.land/docs/how_to_guides/manifest_annotations/