Add prototypes folder to test new functionality in (#6081)

# Description of Changes
Add prototypes folder to test new functionality in. This build of the
app is spawnable with `npm run dev:prototypes`.

Currently just contains a very developer-y chat interface to help us
develop & explore the AI backend before we make the frontend for it for
real.

frontend/eslint.config.mjs

@@ -86,6 +86,7 @@ export default defineConfig(
     files: [
       'src/proprietary/**/*.{js,mjs,jsx,ts,tsx}',
       'src/saas/**/*.{js,mjs,jsx,ts,tsx}',
+      'src/prototypes/**/*.{js,mjs,jsx,ts,tsx}',
     ],
     languageOptions: {
       parserOptions: {