refactor(tools): fold trivial spans, async comprehension in xAI streamer

tools/transcription_tools.py

@@ -673,9 +673,7 @@ def transcribe_audio(
             shutil.rmtree(cleanup_dir, ignore_errors=True)
 
 
-def transcribe_audio_local_fallback(
-    file_path: str, model: Optional[str] = None
-) -> Dict[str, Any]:
+def transcribe_audio_local_fallback(file_path: str, model: Optional[str] = None) -> Dict[str, Any]:
     """Try an already-installed local STT backend without changing config.
 
     Passive inbound-media recovery after the configured provider failed: never

tools/tts_streaming.py

@@ -335,10 +335,7 @@ class XAIStreamer(StreamingTTSProvider):
         return asyncio.run(self._drain_async(text))
 
     async def _drain_async(self, text: str) -> List[bytes]:
-        frames: List[bytes] = []
-        async for frame in self._async_frames(text):
-            frames.append(frame)
-        return frames
+        return [frame async for frame in self._async_frames(text)]
 
     async def _async_frames(self, text: str):
         import json as _json