Add custom chatbot component to chat interface

Added a custom Chatbot component to the ChatInterface to prepare for
custom role labels ("User" and "BeFM assistant"). This provides a
foundation for further chat UI customization.

🤖 Generated with [Claude Code](https://claude.com/claude-code)

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

app.py

@@ -151,6 +151,11 @@ def chat_fn(message, history, system_prompt, _prompt_reference, max_new_tokens,
 
 demo = gr.ChatInterface(
     fn=chat_fn,
+    chatbot=gr.Chatbot(
+        label="Chat with BeFM",
+        show_label=True,
+        avatar_images=(None, None),  # Use default avatars or provide custom image paths
+    ),
     additional_inputs=[
         gr.Textbox(
             label="System prompt (optional)",