fix: resolve CI linting and type checking issues

app/cmdparse/extractors.py

@@ -0,0 +1,25 @@
+"""Field extraction utilities."""
+
+from typing import Any, Dict, List
+
+
+def extract_fields(data: List[Dict[str, Any]], fields: List[str]) -> List[Dict[str, Any]]:
+    """Extract specified fields from parsed data."""
+    result = []
+    for item in data:
+        extracted = {}
+        for field in fields:
+            if '.' in field:
+                parts = field.split('.')
+                value = item
+                for part in parts:
+                    if isinstance(value, dict):
+                        value = value.get(part)
+                    else:
+                        value = None
+                        break
+                extracted[field] = value
+            else:
+                extracted[field] = item.get(field)
+        result.append(extracted)
+    return result