refactor: update Dockerfiles and nginx configurations for consistency and optimization

admin/nginx.conf

@@ -0,0 +1,18 @@
+server {
+  listen 80;
+  server_name _;
+
+  root /usr/share/nginx/html;
+  index index.html;
+
+  location / {
+    try_files $uri $uri/ /index.html;
+  }
+
+  location ~* \.(?:js|mjs|css|png|jpg|jpeg|gif|ico|svg|woff2?)$ {
+    expires 1y;
+    access_log off;
+    add_header Cache-Control "public, immutable";
+    try_files $uri =404;
+  }
+}