fix: add user's message to frontend chat store when sending

Previously, only the assistant's response was added to the frontend store.
Now both user and assistant messages are stored, so the conversation
displays correctly in the chat interface.

src/frontend/src/routes/bot/[id]/+page.svelte

@@ -44,6 +44,9 @@
 		
 		isSending = true;
 
+		// Add user's message immediately
+		addMessage({ role: 'user', content: message });
+
 		try {
 			const response = await api.bots.chat(botId, message);
 			addMessage({ role: 'assistant', content: response.response });