fix: remove Python 3.10+ type hint syntax for HF Spaces compatibility

questions/bank.py

@@ -690,9 +690,9 @@ def get_categories() -> list[str]:
 
 
 def filter_questions(
-    categories: list[str] | None = None,
-    difficulty: str | None = None,
-    qtype: str | None = None,
+    categories=None,
+    difficulty=None,
+    qtype=None,
 ) -> list[dict]:
     qs = QUESTIONS
     if categories:

streamlit_app.py

@@ -78,7 +78,7 @@ def _diff_badge(diff: str) -> str:
     return f'<span class="{css}">{label}</span>'
 
 
-def render_question(q: dict, idx: int, key_prefix: str, show_answer: bool = False) -> int | list | None:
+def render_question(q: dict, idx: int, key_prefix: str, show_answer: bool = False):
     """Render a question card. Returns the user's answer or None."""
     qtype = q["type"]