Fix CLI instructions to use npx prefix

Changed "lettabot server" to "npx lettabot server" in:
- Onboarding completion message
- Logout completion message

🐙 Generated with [Letta Code](https://letta.com)

Co-Authored-By: Letta <noreply@letta.com>

src/cli.ts

@@ -315,7 +315,7 @@ async function main() {
         p.log.info('Nothing to delete');
       }
       
-      p.outro('✨ Done! Run `lettabot server` to create a fresh agent.');
+      p.outro('✨ Done! Run `npx lettabot server` to create a fresh agent.');
       break;
     }
       

src/onboard.ts

@@ -1105,5 +1105,5 @@ export async function onboard(): Promise<void> {
     p.log.success(`Agent ID saved: ${config.agentId} (${baseUrl})`);
   }
   
-  p.outro('🎉 Setup complete! Run `lettabot server` to start.');
+  p.outro('🎉 Setup complete! Run `npx lettabot server` to start.');
 }