message: web: Change staging Card Space domain
  This will let staging and production function similarly
  instead of having staging have Card Space usernames at
  a fourth level of domain.
diff: @@ -17,7 +17,7 @@ const universalLinkHostnamesByTarget = {
  };
  const CARD_SPACE_HOSTNAME_SUFFIX = 'card.space';
  -const CARD_SPACE_HOSTNAME_STAGING_SUFFIX = 'space.stack.cards';
  +const CARD_SPACE_HOSTNAME_STAGING_SUFFIX = 'pouty.pizza';
  const CARD_SPACE_HOSTNAME_TEST_SUFFIX = 'space.example.com';
  const cardSpaceHostnameSuffixesByTarget = {
  