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/specs/examples/container-layout.tsx

@@ -0,0 +1,22 @@
+import { Container, Heading } from "@medusajs/ui"
+
+export default function ContainerLayout() {
+  return (
+    <div className="flex h-full w-full">
+      <div className="border-ui-border-base w-full max-w-[216px] border-r p-4">
+        <Heading level="h3">Menubar</Heading>
+      </div>
+      <div className="flex w-full flex-col gap-y-2 px-8 pb-8 pt-6">
+        <Container>
+          <Heading>Section 1</Heading>
+        </Container>
+        <Container>
+          <Heading>Section 2</Heading>
+        </Container>
+        <Container>
+          <Heading>Section 3</Heading>
+        </Container>
+      </div>
+    </div>
+  )
+}