Fix Chatbot initialization and message handling

- Initialize Chatbot with empty list value=[]
- Remove orphaned comment about adding user message to history
- Ensures proper list format from the start

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

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

py/frontend/gradio_app.py

@@ -169,9 +169,6 @@ class PeerToPeerApp:
             version != self.current_version):
             self.update_settings(model, product, version)
         
-        # Add user message to history
-        # Gradio expects list of [user, assistant] pairs, not dicts
-        
         # Save user message to database
         self.history_manager.add_message(
             self.current_conversation_id,
@@ -553,6 +550,7 @@ class PeerToPeerApp:
                 with gr.Column(scale=3):
                     # Chat interface
                     chatbot = gr.Chatbot(
+                        value=[],
                         height=500,
                         show_label=False,
                         elem_id="chatbot",