docs: migrate UI docs (#13245)

* docs: create a new UI docs project (#13233)

* docs: create a new UI docs project

* fix installation errors

* docs: migrate UI docs content to new project (#13241)

* Fix content

* added examples for some components

* finish adding examples

* lint fix

* fix build errors

* delete empty files

* path fixes + refactor

* fix build error

www/apps/ui/middleware.ts

@@ -0,0 +1,15 @@
+import { NextResponse } from "next/server"
+import type { NextRequest } from "next/server"
+
+export function middleware(request: NextRequest) {
+  return NextResponse.rewrite(
+    new URL(
+      `${request.nextUrl.basePath}/md-content${request.nextUrl.pathname.replace("/index.html.md", "")}`,
+      request.url
+    )
+  )
+}
+
+export const config = {
+  matcher: "/:path*/index.html.md",
+}