chore: add Dockerfile and nginx config for Coolify deployment

nginx.conf

@@ -0,0 +1,23 @@
+server {
+  listen 80;
+  server_name _;
+  root /usr/share/nginx/html;
+  index index.html;
+
+  gzip on;
+  gzip_types text/plain text/css application/javascript application/json image/svg+xml;
+  gzip_min_length 256;
+
+  # Cache hashed assets aggressively
+  location /assets/ {
+    expires 1y;
+    add_header Cache-Control "public, immutable";
+    try_files $uri =404;
+  }
+
+  # SPA fallback (single page; no client routing here, but harmless)
+  location / {
+    try_files $uri $uri/ /index.html;
+    add_header Cache-Control "no-cache";
+  }
+}