core: prohibit assigning owner role in channels (#7631)

src/Simplex/Chat/Library/Commands.hs

@@ -2947,6 +2947,8 @@ processChatCommand cxt nm = \case
         throwCmdError "can't change role of multiple members when admins selected, or new role is admin"
       when anyPending $ throwCmdError "can't change role of members pending approval"
       when (anyRelay || newRole == GRRelay) $ throwCmdError "relay role can't be changed"
+      -- TODO [multi-owner] allow once owners are added via link data - until then promoted owner would lack link authority
+      when (useRelays' gInfo && newRole == GROwner) $ throwCmdError "owner role can't be assigned in channels"
       -- TODO allow moderators (needs UI) - relay is rejected above (anyRelay), so drop the GRAdmin floor:
       -- TODO   assertUserGroupRole gInfo (roleRequiredToChange maxRole newRole)
       assertUserGroupRole gInfo $ maximum ([GRAdmin, maxRole, newRole] :: [GroupMemberRole])