Add nginx config for VitePress SPA routing

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

docs/nginx.conf

@@ -0,0 +1,15 @@
+server {
+    listen 80;
+    server_name _;
+    root /usr/share/nginx/html;
+    index index.html;
+
+    location / {
+        try_files $uri $uri/ $uri.html /index.html;
+    }
+
+    location ~* \.(js|css|png|jpg|jpeg|gif|ico|svg|woff|woff2|ttf|eot)$ {
+        expires 1y;
+        add_header Cache-Control "public, immutable";
+    }
+}