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.

CLAUDE.md

@@ -83,14 +83,17 @@ The Drizzle client is in `lib/db/index.ts` (postgres.js driver); the schema is i
 | DB schema | `lib/db/schema.ts` |
 | AppConfig aggregate | `lib/app-config.ts` |
 | Portfolio queries | `lib/portfolio.ts` |
-| Media handling | `lib/media.ts` |
+| Media handling | `lib/media.ts`, `lib/media-storage.ts` |
 | Contact flow | `lib/mail.ts` |
+| SEO (metadata, robots, sitemap, JSON-LD) | `lib/metadata.ts`, `lib/seo-settings.ts`, `app/robots.ts`, `app/sitemap.ts` — see `docs/SEO.md` |
+| Admin session token (middleware + auth) | `lib/admin-session-token.ts` |
 
 ### Documentation to read by task scope
 
 - **Small UI/copy/style fixes**: read only the relevant files
 - **Feature changes**: read `specs/<feature>.md` + `docs/ARCHITECTURE.md` if structure is affected
 - **Cross-cutting/architecture changes**: read `docs/ARCHITECTURE.md`, `docs/DOMAIN_RULES.md`, `docs/FEATURES.md`, and the relevant `specs/` file
+- **SEO / metadata / robots / sitemap**: read `docs/SEO.md` first
 
 Update `docs/` and `specs/` only when the change affects feature scope, business rules, architecture, or public behavior.