feat(admin-web): add web/admin to repo

Initial commit of the Super-Admin web panel (Next.js + TypeScript).
CI admin-web-check job was failing because the directory was never
tracked in git.

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

web/admin/src/app/layout.tsx

@@ -0,0 +1,7 @@
+export default function RootLayout({
+  children,
+}: {
+  children: React.ReactNode;
+}) {
+  return children;
+}