feat: support virtual item detail images and COS access

deploy/nginx-file.conf.example

@@ -1,7 +1,8 @@
 # Include this location in the server block for 101.43.139.56.
-# Preserve /file/access and the token query when forwarding.
-location /file/ {
-    proxy_pass http://127.0.0.1:8080;
+# The public /hera/file/access path maps to Spring's /file/access.
+# Keep the query string intact; do not forward this route directly to COS.
+location /hera/file/ {
+    proxy_pass http://127.0.0.1:8080/file/;
     proxy_set_header Host $host;
     proxy_set_header X-Real-IP $remote_addr;
     proxy_set_header X-Forwarded-Proto $scheme;