How to use fastify-vite with an existing route?

## 💬 How do you render SSR components from an existing Fastify route?

I'd like to simply render a Svelte/React/Vue page from an existing Fastify route and return the HTML to the client.

E.g.

```js
// Uses Vite magic to import the component from a .svelte file and provide a JS object that has a render() method
import HomePage from './HomePage.svelte'

fastify.get('/', async (req, reply) => {
// Do some complicated server-side stuff here...

// Render the home page
const { js, css, html } = await HomePage.render({ /* props */ })

// Inject the js/css/html for the home page into some sort of html template and return
return reply.html(css, js, html)
})
```

From what I can tell of @fastify/fastify-vite, routes are generated by the plugin which means you can't use an existing route alongside it. This seems like it should be straightforward and I'm just missing something.

I'd like to primarily focus on SSR but eventually ship some hydrated components + JS to the client for a richer client-side app, (but still MPA with SSR.)

Thanks!

## Your Environment

- *node version*: 18+
- *fastify version*: >=4.0.0
- *os*: Mac
- *Typescript*