chore: add nginx.conf for Docker static export

Required for serving Next.js static export via nginx in Docker.

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

nginx.conf

@@ -0,0 +1,15 @@
+server {
+    listen 80;
+    server_name _;
+    root /usr/share/nginx/html;
+    index index.html index.htm;
+
+    location / {
+        try_files $uri $uri/ $uri.html =404;
+    }
+
+    error_page 404 /404.html;
+
+    gzip on;
+    gzip_types text/plain text/css application/json application/javascript text/xml application/xml text/javascript;
+}