build: migrate frontend to Vite and Vue 3
Replace the Laravel Mix / Webpack build with Vite and upgrade Vue 2.7 to Vue 3.5, keeping the server-rendered island setup where every .vue_app element is mounted as its own app.
Add a Vite view extension that renders entry point tags from the manifest in production and from the dev server (with HMR) when the hot file is present. RTL keeps a separate app.rtl.css, emitted next to every stylesheet via rtlcss.
Publish jQuery/axios/lodash globals from a dedicated module so libraries that read window.jQuery load after them, switch Bootstrap and flatpickr calls to native APIs, and load Prism in manual mode (currentScript is null in a module). Drop the frontend part of the wysibb editor; the backend stays untouched.