fix(admin): nginx.conf 与 deploy 对齐，避免 assets 回退为 HTML MIME 白屏

Made-with: Cursor

admin/nginx.conf

@@ -0,0 +1,24 @@
+# 与 deploy/admin/default.conf 保持一致（Compose 挂载该文件；镜像内也用此配置）
+# 外层 Nginx 已把 /admin/ 转成 / 转发到本容器，此处 location / 提供 SPA
+server {
+  listen 80;
+  root /usr/share/nginx/html;
+  index index.html;
+
+  # 发版后勿长期缓存入口，否则浏览器保留旧 index.html、却拉新 chunk 名 → 白屏
+  location = /index.html {
+    add_header Cache-Control "no-cache, no-store, must-revalidate";
+    expires -1;
+  }
+
+  location ^~ /assets/ {
+    try_files $uri =404;
+    access_log off;
+    expires 7d;
+    add_header Cache-Control "public, immutable";
+  }
+
+  location / {
+    try_files $uri $uri/ /index.html;
+  }
+}