Add hex converter utility

- To move to separate utility file in the future

stat/utils/extractor.py

@@ -1,11 +1,20 @@
-# File: extractor.py
-# Copyright (C) 2026 Erick Ahmed
-# SPDX-License-Identifier: AGPL-3.0-or-later
-
 import json
 from pathlib import Path
+
+import numpy as np
 import pandas as pd
 
+def to_int(x):
+    """Convert a hex string or integer to int, returning NaN on failure."""
+    if isinstance(x, (int, np.integer)):
+        return int(x)
+    if isinstance(x, str):
+        try:
+            return int(x, 16)
+        except ValueError:
+            return np.nan
+    return np.nan
+
 def extract_id(row: pd.Series) -> str:
     """Extracts PGN from metadata or falls back to CAN ID."""
     meta = row.get('j1939_metadata')
@@ -25,14 +34,3 @@ def load_data(file_path: Path) -> pd.DataFrame:
     df = pd.read_parquet(file_path)
     df['Identifier'] = df.apply(extract_id, axis=1)
     return df
-
-def to_int(x):
-    """Convert a hex string or integer to int, returning NaN on failure."""
-    if isinstance(x, (int, np.integer)):
-        return int(x)
-    if isinstance(x, str):
-        try:
-            return int(x, 16)
-        except ValueError:
-            return np.nan
-    return np.nan