feat(ui): build responsive cookbook, editor and persistent cooking assistant

src/app/loading.tsx

@@ -0,0 +1,12 @@
+export default function Loading() {
+  return (
+    <div className="container">
+      <div className="skeleton skeleton-hero" />
+      <div className="recipe-grid">
+        {[1, 2, 3].map((n) => (
+          <div className="skeleton skeleton-card" key={n} />
+        ))}
+      </div>
+    </div>
+  );
+}