Add Tailwind + shadcn UI primitives; add React Query + Orval client

frontend/src/api/mutator.ts

@@ -0,0 +1,22 @@
+export async function customFetch<T>(
+  url: string,
+  options: RequestInit,
+): Promise<T> {
+  const base = process.env.NEXT_PUBLIC_API_URL;
+  if (!base) throw new Error("NEXT_PUBLIC_API_URL is not set");
+
+  const res = await fetch(`${base}${url}`, {
+    ...options,
+    headers: {
+      "Content-Type": "application/json",
+      ...(options.headers ?? {}),
+    },
+  });
+
+  if (!res.ok) {
+    const text = await res.text().catch(() => "");
+    throw new Error(`${res.status} ${res.statusText}${text ? `: ${text}` : ""}`);
+  }
+
+  return (await res.json()) as T;
+}