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

common/components/filters.py

@@ -62,15 +62,9 @@ def _filter_parse(filter_json: str) -> dict:
         return {}
 
 
-def _extract_labeled(items: list) -> list[LabeledOption]:
-    """Convert a list of bare values or ``{id, label}`` dicts to ``(value, label)`` pairs."""
-    result = []
-    for item in items:
-        if isinstance(item, dict):
-            result.append((str(item.get("id", "")), str(item.get("label", ""))))
-        else:
-            result.append((str(item), ""))
-    return result
+def _extract_labeled(items: list[dict]) -> list[LabeledOption]:
+    """Convert a list of ``{id, label}`` dicts to ``(value, label)`` pairs."""
+    return [(str(item["id"]), str(item["label"])) for item in items]
 
 
 def _filter_get_choice(existing: dict, field: str) -> FilterChoice: