Show which model name and provider is used in user message.

app/components/chat/UserMessage.tsx

@@ -17,5 +17,5 @@ export function UserMessage({ content }: UserMessageProps) {
 }
 
 function sanitizeUserMessage(content: string) {
-  return content.replace(modificationsRegex, '').replace(MODEL_REGEX, '').replace(PROVIDER_REGEX, '').trim();
+  return content.replace(modificationsRegex, '').replace(MODEL_REGEX, 'Using: $1').replace(PROVIDER_REGEX, ' ($1)\n\n').trim();
 }