feat: soft-delete for teamer accounts

addresses #869dv9br3

src/Security/Voter/ImpersonationVoter.php

@@ -44,6 +44,12 @@ class ImpersonationVoter extends Voter
             return false;
         }
 
+        // a deleted account is excluded from every process, so impersonating it must not
+        // become a way back into the teamer area
+        if (true === $targetUser->isDeleted()) {
+            return false;
+        }
+
         // Admin is the only role allowed to impersonate
         if (false === $this->security->isGranted('ROLE_ADMIN')) {
             return false;