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/FEATURES.md

@@ -14,8 +14,11 @@
 - Contact form with:
   - validation
   - email delivery
-- Success page after contact submission
-- Maintenance redirect flow
+- Success page after contact submission (noindex)
+- Maintenance redirect flow (bypass requires a *signed* admin session cookie)
+- SEO: localized metadata with canonical + hreflang, OG/Twitter cards (project
+  cover as share image), JSON-LD (WebSite + Person/Organization, CreativeWork per
+  project), dynamic `robots.txt` and hreflang `sitemap.xml` — see `docs/SEO.md`
 
 ### Admin
 
@@ -24,8 +27,12 @@
 - Portfolio category management
 - Portfolio project creation and editing
 - Section and asset management inside each project
-- Media library with usage bindings
-- Site settings management
+- Media library with usage bindings (uploads are magic-byte checked, SVGs are
+  sanitized and served sandboxed)
+- Site settings management (Brand, Localization, SEO)
+- SEO page: indexing switch, Search Console/Bing verification, X handle,
+  structured-data identity, per-locale keywords, readiness checklist and links
+  to sitemap/robots/manifest
 - SMTP settings and test email
 - Marquee settings
 - Maintenance toggle