feat: turbostarter boilerplate

Production-ready Next.js boilerplate with:
- Runtime env validation (fail-fast on missing vars)
- Feature-gated config (S3, Stripe, email, OAuth)
- Docker + Coolify deployment pipeline
- PostgreSQL + pgvector, MinIO S3, Better Auth
- TypeScript strict mode (no ignoreBuildErrors)
- i18n (en/es), AI modules, billing, monitoring

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

apps/web/src/lib/query/client.tsx

@@ -0,0 +1,30 @@
+"use client";
+
+import { QueryClientProvider as TanstackQueryClientProvider } from "@tanstack/react-query";
+import { ReactQueryDevtools } from "@tanstack/react-query-devtools";
+
+import { createQueryClient } from "./utils";
+
+import type { QueryClient } from "@tanstack/react-query";
+
+let clientQueryClientSingleton: QueryClient | undefined = undefined;
+export const getQueryClient = () => {
+  if (typeof window === "undefined") {
+    // Server: always make a new query client
+    return createQueryClient();
+  } else {
+    // Browser: use singleton pattern to keep the same query client
+    return (clientQueryClientSingleton ??= createQueryClient());
+  }
+};
+
+export function QueryClientProvider(props: { children: React.ReactNode }) {
+  const queryClient = getQueryClient();
+
+  return (
+    <TanstackQueryClientProvider client={queryClient}>
+      {props.children}
+      <ReactQueryDevtools />
+    </TanstackQueryClientProvider>
+  );
+}