feat: 新增 Nginx 配置文件，支持 WebSocket 代理与健康检查

backend/nginx/nginx.conf

@@ -0,0 +1,47 @@
+events {
+    worker_connections 1024;
+}
+
+http {
+    include /etc/nginx/mime.types;
+    default_type application/octet-stream;
+
+    log_format main '$remote_addr - $remote_user [$time_local] "$request" '
+                      '$status $body_bytes_sent "$http_referer" '
+                      '"$http_user_agent" "$http_x_forwarded_for"';
+
+    access_log /var/log/nginx/access.log main;
+    error_log /var/log/nginx/error.log warn;
+
+    sendfile on;
+    tcp_nopush on;
+    tcp_nodelay on;
+    keepalive_timeout 65;
+
+    upstream gateway {
+        server gateway:8080;
+    }
+
+    server {
+        listen 80;
+        server_name localhost;
+
+        location / {
+            proxy_pass http://gateway;
+            proxy_http_version 1.1;
+            proxy_set_header Upgrade $http_upgrade;
+            proxy_set_header Connection "upgrade";
+            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;
+            proxy_cache_bypass $http_upgrade;
+        }
+
+        location /health {
+            stub_status on;
+            access_log off;
+            allow all;
+        }
+    }
+}