- 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
- Add hash conflict detection in import_block to delete existing blocks with same hash
- Add hash conflict cleanup in import_chain before importing blocks
- Add logging for hash conflict deletions showing affected chains
- Add WAL file permission setting in init_db for .db-shm and .db-wal files
- Add test_import_chain_clears_hash_conflicts_across_chains to verify cross-chain hash cleanup
- Add chain_id field to Block creation in import_block endpoint
- Remove await from synchronous session.commit in import_block
- Add _serialize_optional_timestamp helper to handle various timestamp formats
- Add _parse_datetime_value helper with proper datetime parsing and error handling
- Add _select_export_blocks to filter duplicate blocks by height during export
- Add _dedupe_import_blocks to filter
