Remove bare-value fallback from _extract_labeled

The JS always emits {id, label} objects now; the else branch was dead code
and the docstring was wrong. Update the remaining test that was still
passing bare strings.

https://claude.ai/code/session_01EyAJcMoDktLrY9tSbdHViA

tests/test_filters.py

@@ -293,7 +293,7 @@ class TestFilterBarRendering:
         html = str(
             FilterBar(
                 filter_json=json.dumps(
-                    {"status": {"value": ["f"], "modifier": "INCLUDES"}}
+                    {"status": {"value": [{"id": "f", "label": "Finished"}], "modifier": "INCLUDES"}}
                 ),
             )
         )