chore: remove em-dashes from comments

Author: SAY-5

cli/serve/app.py

@@ -271,7 +271,7 @@ async def endpoint(request: ChatCompletionRequest):
         except Exception:
             # Catch-all for any unexpected errors. Log the full traceback
             # server-side (operators must be able to diagnose the 500), and
-            # return a generic message to the client — the raw `str(e)` can
+            # return a generic message to the client, the raw `str(e)` can
             # leak file paths / internal state across the API boundary
             # (#991).
             logger.exception("Unhandled error in chat-completion handler")