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.

docs/ARCHITECTURE.md

@@ -181,8 +181,8 @@ i18n/routing.ts
 Admin routing  
 lib/admin-routing.ts
 
-Prisma access  
-lib/prisma.ts
+Database access (Drizzle)  
+lib/db/index.ts, lib/db/schema.ts
 
 Application configuration  
 lib/app-config.ts
@@ -191,7 +191,13 @@ Portfolio logic
 lib/portfolio.ts
 
 Media handling  
-lib/media.ts
+lib/media.ts (DB), lib/media-storage.ts (filesystem + content validation), lib/media-service.ts
+
+SEO / metadata  
+lib/metadata.ts, lib/seo-settings.ts, lib/seo-report.ts, app/robots.ts, app/sitemap.ts (docs/SEO.md)
+
+Admin session token (shared by middleware and server auth)  
+lib/admin-session-token.ts
 
 ---