Changes:
- Use pdftract-test-glibc:1.78 image (has aws/b2 CLI preinstalled)
- Use b2-readonly secret instead of armor-secrets
- Update env var names to ARMOR_ACCESS_KEY_ID/ARMOR_SECRET_ACCESS_KEY
- Remove apt-get install step (tools already in image)
The cer-diff tool was already implemented in a previous commit.
This commit fixes the image and secret references per the bead spec.
References pdftract-2t9 acceptance criteria:
- regression-corpus step runs on every PR (✓ already in workflow)
- Uses pdftract-test-glibc:1.78 image (✓ fixed)
- Uses b2-readonly secret (✓ fixed)
Co-Authored-By: Claude Opus 4.7 <noreply@anthropic.com>
