ADDED - Admin SEO page, robots/sitemap hardening and media/maintenance security fixes

SEO
- New Settings > SEO admin page (seo_settings in app_config): indexing switch,
  Google/Bing verification, X handle, JSON-LD identity (Person/Organization,
  sameAs), per-locale keywords, readiness checklist and open links for
  sitemap.xml / robots.txt / manifest.
- robots.txt is now dynamic: disallows admin, api, success and coming-soon
  paths; blocks everything while indexing is off or maintenance is on.
- sitemap.xml carries hreflang alternates per URL, lists only categories with
  published projects, and is empty while hidden.
- Metadata: robots + verification meta, og:locale in de_DE/en_US/ar_AR form,
  alternateLocale, twitter site/creator, project cover as OG image with
  article type, noindex on /success and /coming-soon.
- JSON-LD: WebSite + publisher graph on all public pages, CreativeWork per
  project (view-mode independent).

Security
- Maintenance bypass now requires a correctly signed admin cookie; the
  middleware previously only checked the cookie existed. Token helpers moved
  to lib/admin-session-token.ts (shared by proxy.ts and lib/admin-auth.ts).
- Media uploads: magic-byte validation against the declared type, SVG
  sanitization (script/handlers/foreignObject/javascript: rejected), upload
  folder sanitized, kind inferred from the real file.
- Media route: fixed prefix-based path check that accepted sibling
  directories, unknown extensions return 404, nosniff header, CSP sandbox on
  SVG, gif content type added.
- External media URLs: protocol-relative (//host) URLs rejected.

Portfolio
- Project and category slugs share /portfolio/[slug]; saving now rejects a
  slug already used on the other side instead of silently shadowing it.

Tooling/docs
- Lint: ignore scripts/legacy-prisma-seed.cjs, drop unused import.
- New docs/SEO.md; FEATURES, ARCHITECTURE (Drizzle instead of Prisma), admin
  spec and CLAUDE.md updated.
- Tests for all of the above (unit + integration); suite green.

app/_admin/site-settings/seo/page.tsx

@@ -0,0 +1,104 @@
+import { redirect } from "next/navigation";
+
+import { MotionFade } from "@/components/motion-fade";
+import { SeoSettingsForm } from "@/components/admin/seo-settings-form";
+import { AdminDashboardShell } from "@/components/admin/admin-dashboard-shell";
+import { readFlash } from "@/lib/admin-feedback";
+import { clearAdminSessionCookie, isAdminAuthenticated } from "@/lib/admin-auth";
+import { buildSiteUrl, getAdminAppPath } from "@/lib/admin-routing";
+import {
+  getMaintenanceMode,
+  getSeoSettings,
+  getSiteSettings,
+  getSiteSettingsMediaBindings,
+} from "@/lib/app-config";
+import { getSiteUrl } from "@/lib/metadata";
+import { INTERNAL_MANIFEST_PATH } from "@/lib/site-icons";
+import { getPublishedPortfolioProjects } from "@/lib/portfolio";
+import { buildSeoChecklist } from "@/lib/seo-report";
+import buildSitemap from "@/app/sitemap";
+
+import { saveSeoSettingsAction } from "../actions";
+
+export const dynamic = "force-dynamic";
+
+const copy = {
+  title: "SEO",
+  subtitle: "Indexierung, Verifizierung, strukturierte Daten, Sitemap und robots.txt.",
+  overview: "Uebersicht",
+  maintenance: "Wartungsmodus",
+  uiKit: "UI Kit",
+  media: "Media",
+  siteSettings: "Settings",
+  brandSettings: "Brand",
+  localizationSettings: "Localization",
+  seoSettings: "SEO",
+  smtp: "SMTP",
+  portfolio: "Portfolio",
+  logout: "Ausloggen",
+  backToSite: "Zur Website",
+};
+
+export default async function AdminSeoSettingsPage({
+  searchParams,
+}: {
+  searchParams?: Promise<{ success?: string; error?: string }>;
+}) {
+  const flash = readFlash(await searchParams);
+
+  if (!(await isAdminAuthenticated())) {
+    redirect(getAdminAppPath("/"));
+  }
+
+  async function logoutAction() {
+    "use server";
+
+    await clearAdminSessionCookie();
+    redirect(getAdminAppPath("/"));
+  }
+
+  const [seo, siteSettings, bindings, maintenanceEnabled, projects, sitemapEntries] = await Promise.all([
+    getSeoSettings(),
+    getSiteSettings(),
+    getSiteSettingsMediaBindings(),
+    getMaintenanceMode(),
+    getPublishedPortfolioProjects().catch(() => []),
+    buildSitemap().catch(() => []),
+  ]);
+
+  const checks = buildSeoChecklist({
+    seo,
+    settings: siteSettings,
+    bindings,
+    maintenanceEnabled,
+    publishedProjectCount: projects.length,
+    sitemapEntryCount: sitemapEntries.length,
+    siteUrl: getSiteUrl().origin,
+  });
+
+  return (
+    <AdminDashboardShell
+      copy={copy}
+      active="site-settings"
+      flash={flash}
+      siteSettingsChild="seo"
+      logoutAction={logoutAction}
+      headerTitle={copy.title}
+      headerDescription={copy.subtitle}
+    >
+      <MotionFade delay={0.16}>
+        <SeoSettingsForm
+          action={saveSeoSettingsAction}
+          settings={seo}
+          checks={checks}
+          sitemapEntryCount={sitemapEntries.length}
+          links={{
+            sitemap: buildSiteUrl("/sitemap.xml"),
+            robots: buildSiteUrl("/robots.txt"),
+            manifest: buildSiteUrl(INTERNAL_MANIFEST_PATH),
+          }}
+        />
+      </MotionFade>
+    </AdminDashboardShell>
+  );
+}