Add indicator in chat log for assistant responses

Now it is clear when the assistant responds in the terminal interface.

assistant.py

@@ -179,10 +179,13 @@ def chat2(args, user_input, stream=True):
     if parse_commands(user_input):
         result = ''
     elif args.reflect:
+        print('assistant: ', end='')
         result = reflection_mode(user_input, stream)
     else:
+        print('assistant: ', end='')
         result = chat(user_input, stream)
 
+    if result != '':
         conversation += 'user: ' + user_input + '\n'
         conversation += 'assistant: ' + result + '\n'
     return result