feat(api): add pagination to messages endpoint and improve chat API robustness

- Add pagination support to /api/conversations/[id]/messages with limit and before query params, returning hasMore and cursor for efficient message fetching
- Enhance /api/ollama/chat by adding non-blocking Ollama availability check and conditionally disabling debug logging in production环境下Featured

lib/ollama.ts

@@ -83,7 +83,7 @@ export async function chatWithStream(
       ? [{ role: "system", content: system }, ...messages]
       : messages,
     stream: true,
-    options,
+    options: { ...(options || {}), keep_alive: "5m" },
   };
 
   // Adicionar tools se fornecidos