primefaces/primevue ? reverse-engineered prompt

Build me a polished Vue 3 UI component library with a clean demo site, something like a modern set of reusable components for building admin dashboards and app interfaces. I want the basics covered well, like buttons, inputs, dialogs, dropdowns, tabs, menus, selects, date pickers, tables, data grids, trees, and tree tables, with consistent styling, good defaults, and easy theming.

Please make the components feel production ready, with accessibility in mind, sensible props and events, and examples that show how to use them in real pages. Include a showcase app so I can browse the components and see them working together, and make sure it plays nicely with Vue 3 and Nuxt style projects. If you need to, look up current docs online for any tricky Vue patterns or best practices.

Keep the codebase organized and easy to extend, and make the library feel like something that could be used in a real product right away.