feat: 交付官方 Docker 运行时，外观改背景图并下线自定义 CSS/JS

站点/后台分轨背景与用户列表排序一并落地；生产 CORS 改走 SITE_URL，健康检查带版本号。

Co-authored-by: Cursor <cursoragent@cursor.com>

deploy/nginx.example.conf

@@ -0,0 +1,49 @@
+# 宿主机 Nginx 示例（官方 Compose 不含反代）。
+# 页面、/api、/api/ws、/uploads 必须同一 Host；/api/ws 直达 Go，不要进 Next。
+# 把 bbs.example.com 与证书路径换成实际值，upstream 端口与 .env 里 JIANG13_*_PORT 一致。
+
+map $http_upgrade $connection_upgrade {
+    default upgrade;
+    ''      close;
+}
+
+server {
+    listen 443 ssl http2;
+    server_name bbs.example.com;
+
+    # ssl_certificate     /path/to/fullchain.pem;
+    # ssl_certificate_key /path/to/privkey.pem;
+
+    client_max_body_size 512m;
+
+    location /api/ {
+        proxy_pass http://127.0.0.1:3001;
+        proxy_http_version 1.1;
+        proxy_set_header Host $host;
+        proxy_set_header X-Forwarded-Proto $scheme;
+        proxy_set_header X-Forwarded-For $proxy_add_x_forwarded_for;
+        proxy_set_header Upgrade $http_upgrade;
+        proxy_set_header Connection $connection_upgrade;
+        proxy_read_timeout 3600s;
+    }
+
+    location /uploads/ {
+        proxy_pass http://127.0.0.1:3001;
+        proxy_set_header Host $host;
+        proxy_set_header X-Forwarded-Proto $scheme;
+        proxy_set_header X-Forwarded-For $proxy_add_x_forwarded_for;
+    }
+
+    location /health {
+        proxy_pass http://127.0.0.1:3001;
+        proxy_set_header Host $host;
+    }
+
+    location / {
+        proxy_pass http://127.0.0.1:3000;
+        proxy_http_version 1.1;
+        proxy_set_header Host $host;
+        proxy_set_header X-Forwarded-Proto $scheme;
+        proxy_set_header X-Forwarded-For $proxy_add_x_forwarded_for;
+    }
+}