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/SEO.md

@@ -0,0 +1,83 @@
+# SEO
+
+How search visibility works in this project and where each piece is controlled.
+Everything is data-driven from the admin; no code change is needed to adjust
+titles, descriptions, indexing, verification, or structured data.
+
+## Admin: Settings → SEO (`/site-settings/seo`)
+
+Canonical page: `app/_admin/site-settings/seo/page.tsx` (mirrored under
+`app/admin-internal/` and `app/root/`). Form: `components/admin/seo-settings-form.tsx`.
+Action: `saveSeoSettingsAction` in `app/_admin/site-settings/actions.ts`.
+
+Stored as one JSON blob in `app_config` under key `seo_settings`
+(`lib/seo-settings.ts` parses/normalizes; `lib/app-config.ts` exposes
+`getSeoSettings` / `updateSeoSettings`).
+
+| Field | Effect |
+|---|---|
+| Indexierung erlauben | Off → `noindex,nofollow` meta on every page, `robots.txt` disallows `/`, `sitemap.xml` becomes empty. Maintenance mode forces the same automatically. |
+| Google / Bing Verification | `<meta name="google-site-verification">` and `<meta name="msvalidate.01">` on all pages. Tokens are restricted to `[A-Za-z0-9_-]`. |
+| X / Twitter Handle | `twitter:site` + `twitter:creator`. |
+| Strukturierte Daten | Type (`Person` / `Organization`), name, job title/slogan, `sameAs` profile URLs → JSON-LD publisher on every public page. |
+| Keywords (per locale) | `<meta name="keywords">` per language. |
+
+The page also shows a **checklist** (`lib/seo-report.ts`) — indexing state, public
+URL, meta description length per locale, OG image, favicon, verification,
+structured data, published projects, sitemap URL count — and **open buttons** for
+`/sitemap.xml`, `/robots.txt`, `/manifest.webmanifest`.
+
+Titles, descriptions and the title template per locale live under
+**Settings → Localization**; logos, favicon and the default OG image under
+**Settings → Brand**.
+
+## Generated files
+
+- `app/robots.ts` → `/robots.txt`. Indexable: allow `/`, disallow admin
+  (`/admin-internal`, `/root`), `/api/`, `/success`, `/coming-soon` (+ locale
+  variants), plus the sitemap URL. Not indexable (setting off or maintenance):
+  disallow everything.
+- `app/sitemap.ts` → `/sitemap.xml`. One entry per locale for home, about,
+  portfolio, contact, every category that has published projects, and every
+  published project — each with `xhtml:link hreflang` alternates and `x-default`.
+  Empty while maintenance mode is on or indexing is disabled.
+- `app/manifest.ts` → `/manifest.webmanifest` (icons from Brand settings).
+
+## Per-page metadata (`lib/metadata.ts`)
+
+- `buildAppMetadata()` — root layout: `metadataBase`, robots, verification,
+  keywords, icons, manifest, OG (`og:locale` as `de_DE`/`en_US`/`ar_AR` +
+  `alternateLocale`), Twitter.
+- `buildLocalizedMetadata({...})` — every public page: templated title,
+  description (≤300 chars), canonical + hreflang alternates, robots, OG, Twitter.
+  Options: `image` (page-specific share image), `noIndex`, `type: "article"`,
+  `publishedTime`.
+- Portfolio project pages pass the project **cover** as OG image and `article`
+  type. This is independent of the project's view mode (`GRID` / `STORY` /
+  `CASE_STUDY`), so new view modes inherit full SEO automatically.
+- `/success` and `/coming-soon` are `noindex`.
+
+## Structured data (JSON-LD)
+
+Rendered via `components/seo/json-ld.tsx` (server component; `<` is escaped).
+
+- Site layout: `WebSite` + publisher (`Person` or `Organization`) graph linked by
+  `@id` (`buildSiteJsonLd`).
+- Project page: `CreativeWork` with url, headline, description, image, genre
+  (category), keywords (service label, year), `datePublished`, author `@id`,
+  client as `sourceOrganization` (`buildProjectJsonLd`).
+
+## Slugs
+
+Categories and projects share `/portfolio/[slug]`; categories win at resolve
+time. The admin therefore rejects a project slug that equals an existing
+category slug and vice versa (`app/_admin/portfolio/actions.ts`).
+
+## Operational checklist before launch
+
+1. `NEXT_PUBLIC_SITE_URL` must be the public `https://` origin (canonical base).
+2. Settings → Localization: site name + 50–160 char description in DE/EN/AR.
+3. Settings → Brand: default OG image (1200×630) + favicon.
+4. Settings → SEO: indexing on, verification codes, Person/Organization data.
+5. Maintenance mode off. Verify `/robots.txt` and `/sitemap.xml` from the SEO page.
+6. Submit the sitemap in Google Search Console / Bing Webmaster.