Incorporates review feedback from Rhea, Argus, and Ganymede on PR #2072:
- Added pipeline.db tables to producer/consumer map
- Added API response shapes (endpoints + graph-data.json)
- Added systemd service configuration as schema surface
- Added DB column and API shape rules to backward compatibility
- Clarified that DB/API changes document in PR body (not just schemas/)
- Added legacy alias verification request for Epimetheus
Replaces closed PR #2072.
Pentagon-Agent: Theseus <24DE7DA0-E4D5-4023-B1A2-3F736AFF4EEE>
