fix(shop): use production API via same-origin nginx proxy

Hardcoded localhost:5000 broke shop.zea.lt; wire env fileReplacements
and proxy /api + /uploads to the API container.

docker/nginx-spa.conf

@@ -4,6 +4,25 @@ server {
   root /usr/share/nginx/html;
   index index.html;
 
+  # Browser calls same-origin /api and /uploads; proxy to API container.
+  location /api/ {
+    proxy_pass http://api:8080/api/;
+    proxy_http_version 1.1;
+    proxy_set_header Host $host;
+    proxy_set_header X-Real-IP $remote_addr;
+    proxy_set_header X-Forwarded-For $proxy_add_x_forwarded_for;
+    proxy_set_header X-Forwarded-Proto $scheme;
+  }
+
+  location /uploads/ {
+    proxy_pass http://api:8080/uploads/;
+    proxy_http_version 1.1;
+    proxy_set_header Host $host;
+    proxy_set_header X-Real-IP $remote_addr;
+    proxy_set_header X-Forwarded-For $proxy_add_x_forwarded_for;
+    proxy_set_header X-Forwarded-Proto $scheme;
+  }
+
   location / {
     try_files $uri $uri/ /index.html;
   }