Add chain_id field to all block import test requests

- Add chain_id parameter to importBlock requests in all verification tests
- Update test_block_import.py to use high block heights to avoid conflicts with existing chain
- Simplify test_block_import.py to focus on core validation (hash, parent, conflict)
- Fix test_block_import_complete.py to use head block instead of block 1 for existing block test
- Update expected response format from status field to success field

tests/verification/test_minimal.py

@@ -36,7 +36,8 @@ def test_minimal():
         "proposer": "test-proposer",
         "timestamp": timestamp,
         "tx_count": 0,
-        "transactions": []
+        "transactions": [],
+        "chain_id": CHAIN_ID
     }
     
     print("Testing with empty transactions list...")