added asset manegement

frontend/src/pages/admin/assets.astro

@@ -0,0 +1,10 @@
+---
+import AdminLayout from '../../layouts/AdminLayout.astro';
+import AssetManager from '../../components/AssetManager.astro';
+---
+
+<AdminLayout title="Asset Library">
+    <p slot="header-subtitle" class="mt-2 text-sm md:text-base text-subtext1">Manage your uploaded images and files.</p>
+    
+    <AssetManager mode="manage" />
+</AdminLayout>