fix: claude code system prompt for oauth

server.js

@@ -54,7 +54,7 @@ app.post('/api/chat', async (req, res) => {
                 model: modelId,
                 max_tokens: 8192,
                 stream: true,
-                system: 'You are Claude, a helpful assistant. Respond directly and concisely.',
+                system: "You are Claude Code, Anthropic's official CLI for Claude.",
                 messages: [{ role: 'user', content: text }],
             }),
         });