Revert "Add missing admin action files and navigation links"

This reverts commit 41be6835bf.

src/app/admin/loading.tsx

@@ -1,10 +1,7 @@
 export default function AdminLoading() {
   return (
     <div style={{ display: "flex", justifyContent: "center", padding: "4rem 0" }}>
-      <div
-        className="animate-spin w-8 h-8 border-4 rounded-full"
-        style={{ borderColor: "var(--color-primary)", borderTopColor: "transparent" }}
-      />
+      <div className="animate-spin w-8 h-8 border-4 rounded-full" style={{ borderColor: "var(--color-primary)", borderTopColor: "transparent" }} />
     </div>
   );
 }