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.

lib/admin-auth.ts

@@ -1,4 +1,4 @@
-import { createHash, createHmac, timingSafeEqual } from "crypto";
+import { createHash, timingSafeEqual } from "crypto";
 import { cookies, headers } from "next/headers";
 import { redirect } from "next/navigation";
 
@@ -7,9 +7,13 @@ import { and, eq, like, lt } from "drizzle-orm";
 import { db } from "./db";
 import { appConfig } from "./db/schema";
 import { getAdminAppPath } from "./admin-routing";
+import {
+  ADMIN_SESSION_COOKIE as SHARED_ADMIN_SESSION_COOKIE,
+  buildAdminSessionToken,
+  verifyAdminSessionToken,
+} from "./admin-session-token";
 
-export const ADMIN_SESSION_COOKIE = "moh_admin_session";
-const ADMIN_SESSION_VALUE = "superadmin";
+export const ADMIN_SESSION_COOKIE = SHARED_ADMIN_SESSION_COOKIE;
 const MAX_FAILED_ATTEMPTS = 5;
 const LOCKOUT_SECONDS = 15 * 60;
 const ADMIN_LOCKOUT_KEY_PREFIX = "admin_lockout";
@@ -91,34 +95,12 @@ function getAdminCookieDomain(): string | undefined {
   return hostname ? `.${hostname}` : undefined;
 }
 
-function signValue(value: string): string {
-  return createHmac("sha256", getSecret()).update(value).digest("hex");
-}
-
 function buildToken(): string {
-  return `${ADMIN_SESSION_VALUE}.${signValue(ADMIN_SESSION_VALUE)}`;
+  return buildAdminSessionToken();
 }
 
 function verifyToken(token: string): boolean {
-  const parts = token.split(".");
-  if (parts.length !== 2) {
-    return false;
-  }
-
-  const [value, signature] = parts;
-  if (value !== ADMIN_SESSION_VALUE) {
-    return false;
-  }
-
-  const expected = signValue(value);
-  const left = Buffer.from(signature);
-  const right = Buffer.from(expected);
-
-  if (left.length !== right.length) {
-    return false;
-  }
-
-  return timingSafeEqual(left, right);
+  return verifyAdminSessionToken(token);
 }
 
 async function getClientIp(): Promise<string> {