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/next.config.mjs

@@ -0,0 +1,10 @@
+import createNextIntlPlugin from "next-intl/plugin";
+
+const withNextIntl = createNextIntlPlugin("./src/i18n/request.ts");
+
+/** @type {import('next').NextConfig} */
+const nextConfig = {
+  output: "standalone",
+};
+
+export default withNextIntl(nextConfig);