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/app-config.ts

@@ -67,6 +67,13 @@ import {
   syncMarqueeSettingsToGermanSource,
   type MarqueeSettings,
 } from "./marquee-settings";
+import { SEO_SETTINGS_KEY, buildDefaultSeoSettings, parseSeoSettingsValue, type SeoSettings } from "./seo-settings";
+export {
+  SEO_SETTINGS_KEY,
+  buildDefaultSeoSettings,
+  parseSeoSettingsValue,
+  type SeoSettings,
+} from "./seo-settings";
 
 // Small helpers over the app_config key/value table (Drizzle).
 async function readConfigValue(key: string): Promise<string | undefined> {
@@ -150,6 +157,18 @@ export async function updateMarqueeSettings(settings: MarqueeSettings): Promise<
   await upsertConfig(MARQUEE_SETTINGS_KEY, JSON.stringify(normalizedSettings));
 }
 
+export async function getSeoSettings(): Promise<SeoSettings> {
+  try {
+    return parseSeoSettingsValue(await readConfigValue(SEO_SETTINGS_KEY));
+  } catch {
+    return buildDefaultSeoSettings();
+  }
+}
+
+export async function updateSeoSettings(settings: SeoSettings): Promise<void> {
+  await upsertConfig(SEO_SETTINGS_KEY, JSON.stringify(settings));
+}
+
 export async function getSiteSettingsMediaBindings(): Promise<SiteSettingsMediaBindings> {
   try {
     const usages = await db