fix: Address critical linting issues

- Add 'from None' to exception chains for B904 compliance in:
  - label_manager.py (FileNotFoundError)
- Fix imports in snowflake_loader.py

Author: fordN

src/amp/config/label_manager.py

@@ -123,7 +123,7 @@ def hex_to_binary(v):
             )
 
         except FileNotFoundError:
-            raise FileNotFoundError(f'Label CSV file not found: {csv_path}')
+            raise FileNotFoundError(f'Label CSV file not found: {csv_path}') from None
         except Exception as e:
             raise ValueError(f"Failed to load label CSV '{csv_path}': {e}") from e
 

src/amp/loaders/implementations/snowflake_loader.py

@@ -772,13 +772,6 @@ def connect(self) -> None:
             else:
                 # Create dedicated connection (legacy behavior)
                 # Set defaults for connection parameters
-                default_params = {
-                    'login_timeout': 60,
-                    'network_timeout': 300,
-                    'socket_timeout': 300,
-                    'validate_default_parameters': True,
-                    'paramstyle': 'qmark',
-                }
 
                 conn_params = {
                     'account': self.config.account,

tests/integration/test_checkpoint_resume.py

@@ -406,7 +406,7 @@ def test_processed_ranges_table_creation(self, checkpoint_db_connection):
             enabled=True,
             table_prefix='test_amp_',
         )
-        store = DatabaseProcessedRangesStore(config, checkpoint_db_connection)
+        DatabaseProcessedRangesStore(config, checkpoint_db_connection)
 
         cursor = checkpoint_db_connection.cursor()
         cursor.execute("""

tests/integration/test_resilient_streaming.py

@@ -362,7 +362,7 @@ def test_all_resilience_features_together(self):
         batch = pa.record_batch([[1]], schema=schema)
 
         # Multiple successful loads with retries
-        for i in range(3):
+        for _i in range(3):
             # Reset failure mode for each iteration
             loader.current_attempt = 0