Auto-clear conversation when system prompt changes

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

app.py

@@ -981,6 +981,9 @@ with gr.Blocks(title="PromptWork", theme=gr.themes.Soft()) as app:
 
     clear_btn.click(clear_chat, [], [chatbot])
 
+    # Auto-clear conversation when system prompt changes
+    prompt_input.change(clear_chat, [], [chatbot])
+
     # Session log events
     def update_session_dropdown(sessions):
         choices = get_session_choices(sessions)