fix: nginx files.pub.solar proxy_pass host header

hosts/nachtigall/apps/nginx-mastodon-files.nix

@@ -26,7 +26,7 @@ in
             }
 
             resolver 8.8.8.8;
-            proxy_set_header Host $host;
+            proxy_set_header Host ${objStorHost};
             proxy_set_header Connection \'\';
             proxy_set_header Authorization \'\';
             proxy_hide_header Set-Cookie;