feat: initial IPFS Portal — Next.js frontend for remote IPFS node management

Multi-file upload with Quick Upload + Crypto Payment tabs.
Dashboard with live IPFS metrics, Explorer, Peers, Pins, History, Settings pages.
Docker deploy (standalone output), full test suite (16 Playwright tests).
Payment integration via IPFSPortalPayment + MockUSDC contracts on zkSync.

src/app/layout-portal.tsx

@@ -0,0 +1,16 @@
+'use client';
+
+import PortalSidebar from '@/components/PortalSidebar';
+import PortalHeader from '@/components/PortalHeader';
+
+export default function PortalLayout({ children }: { children: React.ReactNode }) {
+  return (
+    <div className="flex min-h-screen">
+      <PortalSidebar />
+      <div className="flex-1 flex flex-col ml-56">
+        <PortalHeader />
+        <main className="flex-1 p-6">{children}</main>
+      </div>
+    </div>
+  );
+}