- Replace all 2,087 uses of datetime.utcnow() across 294 files
- Add UTC import to datetime statements where needed
- Addresses Python 3.12+ deprecation warning (report item #3)
- Add sys import to 29 test files across agent-coordinator, blockchain-event-bridge, blockchain-node, and coordinator-api
- Remove apps/blockchain-event-bridge/tests/test_integration.py (obsolete bridge integration tests)
- Remove apps/coordinator-api/tests/test_integration.py (obsolete API integration tests)
- Implement GPU registration in marketplace_gpu.py with GPURegistry model persistence