Add sys import to test files and remove obsolete integration tests

- 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

apps/blockchain-node/tests/consensus/test_multi_validator_poa.py

@@ -2,6 +2,7 @@
 Tests for Multi-Validator PoA Consensus
 """
 
+import sys
 import pytest
 import asyncio
 from unittest.mock import Mock, patch

apps/blockchain-node/tests/contracts/test_escrow.py

@@ -2,6 +2,7 @@
 Tests for Escrow System
 """
 
+import sys
 import pytest
 import asyncio
 import time

apps/blockchain-node/tests/economics/test_staking.py

@@ -2,6 +2,7 @@
 Tests for Staking Mechanism
 """
 
+import sys
 import pytest
 import time
 from decimal import Decimal

apps/blockchain-node/tests/network/test_discovery.py

@@ -2,6 +2,7 @@
 Tests for P2P Discovery Service
 """
 
+import sys
 import pytest
 import asyncio
 from unittest.mock import Mock, patch

apps/blockchain-node/tests/network/test_hub_manager.py

@@ -2,6 +2,7 @@
 Tests for Hub Manager with Redis persistence
 """
 
+import sys
 import pytest
 import asyncio
 from unittest.mock import Mock, AsyncMock, patch

apps/blockchain-node/tests/network/test_island_join.py

@@ -2,6 +2,7 @@
 Tests for Island Join functionality
 """
 
+import sys
 import pytest
 import asyncio
 from unittest.mock import Mock, AsyncMock, patch, MagicMock

apps/blockchain-node/tests/security/test_database_security.py

@@ -2,6 +2,7 @@
 Security tests for database access restrictions.
 
 Tests that database manipulation is not possible without detection.
+import sys
 """
 
 import os

apps/blockchain-node/tests/security/test_state_root.py

@@ -2,6 +2,7 @@
 Security tests for state root verification.
 
 Tests that state root verification prevents silent tampering.
+import sys
 """
 
 import pytest

apps/blockchain-node/tests/security/test_state_transition.py

@@ -2,6 +2,7 @@
 Security tests for state transition validation.
 
 Tests that balance changes only occur through validated transactions.
+import sys
 """
 
 import pytest

apps/blockchain-node/tests/test_consensus.py

@@ -2,6 +2,7 @@
 
 from __future__ import annotations
 
+import sys
 import asyncio
 import pytest
 from datetime import datetime, timedelta

apps/blockchain-node/tests/test_force_sync_endpoints.py

@@ -2,6 +2,7 @@ import hashlib
 from contextlib import contextmanager
 from datetime import datetime
 
+import sys
 import pytest
 from sqlmodel import Session, SQLModel, create_engine, select
 

apps/blockchain-node/tests/test_gossip_broadcast.py

@@ -2,6 +2,7 @@ from __future__ import annotations
 
 import asyncio
 
+import sys
 import pytest
 from fastapi.testclient import TestClient
 

apps/blockchain-node/tests/test_gossip_network.py

@@ -2,6 +2,7 @@
 
 from __future__ import annotations
 
+import sys
 import pytest
 import asyncio
 from typing import Generator, Any

apps/blockchain-node/tests/test_guardian_contract.py

@@ -2,6 +2,7 @@
 
 from __future__ import annotations
 
+import sys
 import pytest
 import tempfile
 import shutil

apps/blockchain-node/tests/test_mempool.py

@@ -2,6 +2,7 @@
 
 import json
 import os
+import sys
 import tempfile
 import time
 import pytest

apps/blockchain-node/tests/test_models.py

@@ -2,6 +2,7 @@ from __future__ import annotations
 
 import pytest
 from sqlmodel import Session
+import sys
 
 from aitbc_chain.models import Block, Receipt
 from aitbc_chain.models import Transaction as ChainTransaction

apps/blockchain-node/tests/test_observability_dashboards.py

@@ -2,6 +2,7 @@
 
 from __future__ import annotations
 
+import sys
 import json
 from pathlib import Path
 

apps/blockchain-node/tests/test_sync.py

@@ -2,6 +2,7 @@
 
 import hashlib
 import time
+import sys
 import pytest
 from datetime import datetime
 from contextlib import contextmanager

apps/blockchain-node/tests/test_websocket.py

@@ -2,6 +2,7 @@ from __future__ import annotations
 
 import asyncio
 from contextlib import ExitStack
+import sys
 
 from fastapi.testclient import TestClient