Prefer node-fetch instead of native

src/endpoints/openrouter.js

@@ -1,4 +1,5 @@
 import express from 'express';
+import fetch from 'node-fetch';
 
 export const router = express.Router();
 const API_OPENROUTER = 'https://openrouter.ai/api/v1';

src/endpoints/tokenizers.js

@@ -3,6 +3,7 @@ import path from 'node:path';
 import { Buffer } from 'node:buffer';
 
 import express from 'express';
+import fetch from 'node-fetch';
 import { sync as writeFileAtomicSync } from 'write-file-atomic';
 
 import { Tokenizer } from '@agnai/web-tokenizers';