fix: remove nginx backend proxy - traefik handles routing, fixes host not found error

frontend/nginx.conf

@@ -12,16 +12,7 @@ server {
         add_header Content-Type text/plain;
     }
 
-    # Proxy API calls to backend (handled by Traefik, but keep for direct access)
-    location /api/ {
-        proxy_pass http://backend:5000;
-        proxy_set_header Host $host;
-        proxy_set_header X-Real-IP $remote_addr;
-        proxy_set_header X-Forwarded-For $proxy_add_x_forwarded_for;
-        proxy_set_header X-Forwarded-Proto $scheme;
-    }
-
-    # SPA fallback
+    # SPA fallback — todas as rotas vão para index.html
     location / {
         try_files $uri $uri/ /index.html;
     }