Included types break usage of config object

Prerequisites

[X] I have written a descriptive issue title
[X] I have searched existing issues to ensure the bug has not already been reported

Fastify version

4.26.x

Plugin version

8.14.x

Node.js version

20.x

Operating system

Linux

Operating system version (i.e. 20.04, 11.3, 10)

All

Description

The config object for routes in fastify is typed liberally: it is a union with unknown and you can use it to store arbitrary configuration. However, this module specifies a concrete type for the config option that breaks extensions:

https://github.com/fastify/fastify-swagger/blob/352f7d6c235445731e9843c1f83f313d5320992e/index.d.ts#L56-L58

Steps to Reproduce

import Fastify from 'fastify';
import swagger from '@fastify/swagger';

const fastify = Fastify();

fastify.route({
  url: '/',
  config: { output: 'hello world!' },
  method: 'GET',
  handler(req, reply) {
    reply.send({ hello: 'world' });
  },
});

fastify.listen({ port: 3000 });

Online repro: https://stackblitz.com/edit/node-59kmye?file=package.json,index.ts

Expected Behavior

It should be possible to use fastify-swagger without overwriting config types.

fastify / fastify-swagger

Included types break usage of config object #784