feat: add enterprise app ui layer

frontend/src/components/app/AppEmptyState.tsx

@@ -1,13 +1,17 @@
+import type * as React from 'react'
+
 type AppEmptyStateProps = {
   title: string
   description?: string
+  action?: React.ReactNode
 }
 
-export function AppEmptyState({ title, description }: AppEmptyStateProps) {
+export function AppEmptyState({ title, description, action }: AppEmptyStateProps) {
   return (
     <div className="rounded-lg border border-dashed border-border bg-surface px-4 py-8 text-center">
       <p className="text-sm font-medium text-foreground">{title}</p>
       {description ? <p className="mt-1 text-sm text-muted-foreground">{description}</p> : null}
+      {action ? <div className="mt-4 flex justify-center">{action}</div> : null}
     </div>
   )
 }