fix: increase nginx client_max_body_size for resumable admin uploads

infrastructure/nginx/nginx.conf

@@ -24,6 +24,9 @@ http {
         listen 80 default_server;
         server_name linearvoid.tv localhost 127.0.0.1;
 
+        # Resumable admin upload chunks are 8MB by default; allow safe headroom.
+        client_max_body_size 64m;
+
         root /srv/frontend;
         index index.html;