How does "prefix" works?

I have,
```js
// server.js
await fastify.register(require('./routes/user.routes'), {prefix: '/user'});
```

```js
// user.route.js contains:
const fp = require('fastify-plugin');

async function userRoutes(fastify, options) {
fastify.get('/me', async (request, reply) => {
if (!request.session || !request.session.user) {
return reply.code(401).send({ error: 'Not authenticated' });
}

reply.send(request.session.user);
});

fastify.post('/logout', { preHandler: [fastify.authenticate] }, async (request, reply) => {
if (request.session) {
request.session.destroy();
}
reply.send({ message: 'Logged out' });
});
}

module.exports = fp(userRoutes);
```

but when i go to /prefix/me, i get => 404 error, page not found
but when i go to /me, i get => 401 not authenticated (as expected)

on package.json:

```js
"fastify": "^5.3.3",
"fastify-plugin": "^5.0.1",
"@fastify/cookie": "^11.0.2",
"@fastify/cors": "^11.0.1",
"@fastify/session": "^11.1.0",
"@fastify/swagger": "^9.5.1",
"@fastify/swagger-ui": "^5.2.2",
```