Prod: new admin on admin.*, old admin moves to admin.*/old/

Dockerfile builds apps/backoffice into /srv/admin and the old admin with
base /old/; nginx serves /old/ with its own uncached index.html.
Worker notification links point to the new admin pages (moves, requests,
chats); BACKOFFICE_URL defaults to ADMIN_URL.

Co-Authored-By: Claude Opus 5.5 (1M context) <noreply@anthropic.com>

infra/prod/nginx.conf

@@ -75,6 +75,16 @@ server {
     add_header Cache-Control "no-cache";
   }
 
+  # старая админка: admin.barevclub.com/old/ — своя index.html, тоже без кеша
+  location ^~ /old/ {
+    root /srv/$barev_site;
+    try_files $uri $uri/ /old/index.html;
+    location ~ \.html$ {
+      root /srv/$barev_site;
+      add_header Cache-Control "no-cache";
+    }
+  }
+
   # статика с хешами в имени — кешируем надолго
   location /assets/ {
     root /srv/$barev_site;