feat: add admin content module pages

src/app/admin/events/[id]/event-registrations.tsx

@@ -0,0 +1,40 @@
+'use client'
+
+import { Card, CardContent, CardHeader, CardTitle } from '@/components/ui/card'
+
+interface Registration {
+  id: number
+  userId: number
+  username: string
+  createdAt: Date
+}
+
+interface Props {
+  registrations: Registration[]
+}
+
+export function EventRegistrations({ registrations }: Props) {
+  return (
+    <Card>
+      <CardHeader>
+        <CardTitle>Registrations ({registrations.length})</CardTitle>
+      </CardHeader>
+      <CardContent>
+        {registrations.length === 0 ? (
+          <p className="text-sm text-muted-foreground text-center py-4">No registrations yet.</p>
+        ) : (
+          <div className="divide-y max-h-[400px] overflow-y-auto">
+            {registrations.map((r) => (
+              <div key={r.id} className="flex items-center justify-between py-2">
+                <span className="text-sm font-medium">{r.username}</span>
+                <span className="text-xs text-muted-foreground">
+                  {new Date(r.createdAt).toLocaleString()}
+                </span>
+              </div>
+            ))}
+          </div>
+        )}
+      </CardContent>
+    </Card>
+  )
+}