riddle: switch to abliterated model to stop shadow/fire loops

phi4-mini is too conservative and defaults to the same 2-3 answers.
Use BALL_MODEL (abliterated Llama 3.2) like WYR does.

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

matrixbot/commands.py

@@ -1806,7 +1806,7 @@ async def _generate_riddle() -> dict | None:
             async with session.post(
                 f"{OLLAMA_URL}/api/chat",
                 json={
-                    "model": ASK_MODEL,
+                    "model": BALL_MODEL,
                     "stream": False,
                     "messages": [
                         {"role": "system", "content": system_msg},