Support SSR in Vite dev mode

[jrmajor]

Laravel part handled in inertiajs/inertia-laravel#673.

Adding support for SSR in dev mode would enable developers to discover hydration mismatches/errors before they reach production.

User would need to create additional entrypoint (alongside app.ts and ssr.ts):

import { createInertiaApp } from '@inertiajs/svelte'
import type { AppCallback } from '@inertiajs/svelte/server'

const render: AppCallback = (page) =>
  createInertiaApp({
    page,
    resolve: (name) => import(`./Pages/${name}.svelte`),
  })

export default render

...and add Inertia plugin to Vite:

  import { svelte } from '@sveltejs/vite-plugin-svelte'
  import laravel from 'laravel-vite-plugin'
  import { defineConfig } from 'vite'
+ import inertia from '@inertiajs/core/vite';

 export default defineConfig({
    plugins: [
      laravel({
        input: ['resources/css/app.css', 'resources/js/app.ts'],
        ssr: 'resources/js/ssr.ts',
        refresh: true,
      }),
+     inertia('resources/js/viteSsr.ts'),
      svelte(),
    ],
  })

[harryqt]

This was indeed needed. 🚀