🐛(app-desk) force redirect on mail-domains/[slug]

When we use the static mode, Next.js want that we
build our mail-domains pages at build time.
But we can't do that because users can create a
mail at runtime.

So we redirect thanks to ngnix when we see that
a mail page is not found.

src/frontend/apps/desk/conf/default.conf

@@ -12,6 +12,10 @@ server {
     error_page 404 /teams/[id]/;
   }
 
+  location /mail-domains/ {
+    error_page 404 /mail-domains/[slug]/;
+  }
+
   error_page 404 /404.html;
   location = /404.html {
       internal;