build: add Docker deployment

Created a Dockerfile and nginx configuration and added environment
variables into the codebase to support Docker compose.

ref: N25B-282

nginx.conf

@@ -0,0 +1,26 @@
+server {
+    listen ${PORT};
+    server_name localhost;
+    root /app/www;
+
+    # Security headers
+    add_header X-Frame-Options "SAMEORIGIN";
+    add_header X-XSS-Protection "1; mode=block";
+    add_header X-Content-Type-Options "nosniff";
+
+    # Compression
+    gzip on;
+    gzip_types text/plain text/css application/json application/javascript text/xml application/xml application/xml+rss text/javascript;
+
+    location / {
+        try_files $uri $uri/ /index.html;
+        expires -1;
+    }
+
+    # Cache static assets
+    location /assets {
+        expires 1y;
+        add_header Cache-Control "public, no-transform";
+    }
+}
+