fix: correct docstring for _classify_from_titles return value

analysis/axis_classifier.py

@@ -109,7 +109,7 @@ def _classify_from_titles(titles: List[str]) -> Tuple[Optional[str], float]:
 
     Returns (category_label, confidence) where confidence = fraction of titles
     containing at least one keyword from the winning category.
-    Returns (None, 0.0) if confidence is below _KEYWORD_THRESHOLD.
+    Returns (None, confidence) if confidence is below _KEYWORD_THRESHOLD.
     """
     if not titles:
         return None, 0.0