deploy: Traefik hosts + registry images for shop/admin/api

Publish nginx/API images from CI and deploy on the Pi with
shop.zea.lt, admin.zea.lt, and api.iled.zea.lt.

Co-authored-by: Cursor <cursoragent@cursor.com>

docker/nginx-spa.conf

@@ -0,0 +1,15 @@
+server {
+  listen 80;
+  server_name _;
+  root /usr/share/nginx/html;
+  index index.html;
+
+  location / {
+    try_files $uri $uri/ /index.html;
+  }
+
+  location ~* \.(js|css|png|jpg|jpeg|gif|ico|svg|woff2?)$ {
+    expires 7d;
+    add_header Cache-Control "public";
+  }
+}