Add GPU support with Docker enhancements

- Introduced a `Dockerfile.gpu` for GPU-enabled backend setup.
- Added `docker-compose.gpu.yml` to utilize GPU resources via NVIDIA.
- Fixed Nginx configuration for GPU backend port changes.

nginx/default.conf

@@ -8,13 +8,13 @@ server {
 
   # 所有 /api 请求代理给 backend 容器
   location /api/ {
-    proxy_pass http://backend:8000;
+    proxy_pass http://backend:8483;
     proxy_set_header Host $host;
     proxy_set_header X-Real-IP $remote_addr;
   }
     
    location /static/ {
-    proxy_pass http://backend:8000/static/;
+    proxy_pass http://backend:8483/static/;
     proxy_set_header Host $host;
     proxy_set_header X-Real-IP $remote_addr;