init: static frontend for agency-ai.dev — nginx + YouTube intro video

Static landing page served via nginx 1.27 Alpine container.
Features:
- Fullscreen background image visible from first paint
- YouTube intro video overlay (iframe API, lazy loaded)
- PWA manifest with favicons (48x48, 180x180, 512x512)
- SEO meta tags (OG, Twitter Cards, canonical URL)
- Safety timeout: falls back to static image if YouTube fails

Infrastructure:
- Dockerfile: nginx 1.27 Alpine with custom default.conf
  (gzip, cache headers, security headers X-Frame-Options/nosniff)
- docker-compose.yml: local dev on FRONTEND_PORT (default 8080)
- docker-compose-example/: Dokploy deployment via runtime git clone
  from Gitea, resource limits (256M RAM, 0.5 CPU)

Files:
- index.html: main page with inline CSS + JS (YouTube iframe API)
- default.conf: nginx config (gzip, caching, security headers)
- site.webmanifest: PWA manifest
- assets/imgs/: background image + favicons
- .env.example: FRONTEND_PORT template

docker-compose-example/docker-compose.yml

@@ -0,0 +1,47 @@
+# ============================================================
+# Agencja AI - Docker Compose (Dokploy / manual)
+# ============================================================
+# Dokploy-compatible pattern: uses pre-built image + runtime git clone.
+# Dokploy only copies docker-compose.yml + .env to the server, so local
+# build context with a Dockerfile does not work. This approach matches
+# other working apps on our servers (e.g. wdj-hermes-frontend-matrix).
+#
+# Port hosta: FRONTEND_PORT z .env (domyślnie 8080) → nginx w kontenerze na porcie 80.
+# Dokploy/Traefik routuje po FQDN do wewnętrznego portu 80 kontenera.
+# ============================================================
+
+services:
+  frontend:
+    image: nginx:1.27-alpine
+    container_name: agencja-ai-frontend
+    restart: unless-stopped
+    ports:
+      - "${FRONTEND_PORT:-8080}:80"
+
+    command: >
+      sh -c "
+        apk add --no-cache git &&
+        rm -rf /app &&
+        git clone https://gitea.expert-it.agency-ai.dev/tomasz-syn-grzegorza/site-agency-ai-dev.git /app &&
+        cp /app/index.html /usr/share/nginx/html/index.html &&
+        cp /app/site.webmanifest /usr/share/nginx/html/site.webmanifest &&
+        cp -r /app/assets /usr/share/nginx/html/assets &&
+        rm /etc/nginx/conf.d/default.conf &&
+        cp /app/default.conf /etc/nginx/conf.d/default.conf &&
+        nginx -g 'daemon off;'
+      "
+
+    healthcheck:
+      test: ["CMD", "wget", "-qO-", "http://127.0.0.1:80/"]
+      interval: 30s
+      timeout: 10s
+      retries: 3
+      start_period: 45s
+
+    deploy:
+      resources:
+        limits:
+          memory: 256M
+          cpus: "0.5"
+        reservations:
+          memory: 64M