[minor] Document architecture release boundaries

[libops-agent]

Summary

• distinguish released foundations from target managed ingress and worker architecture
• add a dated status record without inventing missing image digests or CI evidence
• document PRIVATE_RANGES_ONLY routing, package-retention limits, and exact ingress tuning mappings
• keep PPB 0.5.0 source release separate from its missing versioned container

Validation

• make docs-check
• git diff --check