Update nginx config: add health check, improve SPA fallback

nginx.conf

@@ -1,12 +1,18 @@
 server {
-    listen 80;
+    listen 80 default_server;
     server_name _;
     root /usr/share/nginx/html;
     index index.html;
 
-    # Serve static assets
     location / {
-        try_files $uri /index.html;
+        try_files $uri $uri/ /index.html;
+    }
+
+    # Disable logging for health checks
+    location = /health {
+        access_log off;
+        return 200 "OK";
+        add_header Content-Type text/plain;
     }
 
     # Gzip compression