v4.13.13

## Mount Middleware

`app.mount()` is now available as the Mount Middleware, `hono/mount`. It is just a handler, so you register it with `app.all()`:

```ts
import { Router as IttyRouter } from 'itty-router'
import { Hono } from 'hono'
import { mount } from 'hono/mount'

const ittyRouter = IttyRouter()
ittyRouter.get('/hello', () => new Response('Hello from itty-router'))

const app = new Hono()
app.all('/itty-router/*', mount(ittyRouter.handle))
```

`app.mount()` still works in v4 but is deprecated and will be removed in v5. Migrating is a one-line change:

```diff
- app.mount('/itty-router', ittyRouter.handle)
+ app.all('/itty-router/*', mount(ittyRouter.handle))
```

## What's Changed
* test(client): simulate network error for undefined route in parseResponse test in https://github.com/honojs/hono/pull/5439
* docs(request): fix jsdoc comments for some getters in https://github.com/honojs/hono/pull/5445
* fix(jsx): allow JSXNode function component results in https://github.com/honojs/hono/pull/5476
* feat(mount): introduce Mount Middleware and deprecate `app.mount` in https://github.com/honojs/hono/pull/5221

**Full Changelog**: https://github.com/honojs/hono/compare/v4.13.12...v4.13.13