feat: migrate tests to use centralized aitbc package utilities

- Migrate HTTP client usage from requests to aitbc.AITBCHTTPClient in test files
- Update conftest.py to use aitbc path utilities (get_data_path, get_log_path)
- Update test_model_validation.py to use aitbc validators (validate_address, validate_hash)
- Skip HTML scraping files that require raw requests (verify_toggle_removed.py)
- Migrated files: test_payment_integration.py, test_cross_node_blockchain.py, verify_transactions_fixed.py, test_tx_import.py, test_simple_import.py, test_minimal.py, test_block_import_complete.py

tests/verification/test_model_validation.py

@@ -41,6 +41,14 @@ test_data = {
 print("Test data:")
 print(test_data)
 
+# Validate address and hash using aitbc validators
+try:
+    validate_address(test_data["proposer"])
+    validate_hash(test_data["hash"])
+    print("✅ Address and hash validation passed")
+except Exception as e:
+    print(f"⚠️  Validation warning: {e}")
+
 try:
     request = BlockImportRequest(**test_data)
     print("\n✅ Request validated successfully!")