feat(mui): migrate Warehouse overview + replace residual admin-loading loaders with LoadingState

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

src/admin/pages/Projects.tsx

@@ -31,6 +31,7 @@ import {
   DateField,
   StatusChip,
   CheckboxField,
+  LoadingState,
   type DataColumn,
 } from "../ui";
 
@@ -234,11 +235,7 @@ export default function Projects() {
   };
 
   if (isPending) {
-    return (
-      <div className="admin-loading">
-        <div className="admin-spinner" />
-      </div>
-    );
+    return <LoadingState />;
   }
 
   const columns: DataColumn<Project>[] = [