Name uniqueness is global

In the current organizations model, team name uniqueness is a global constraint. This would prevent two different organizations to each have a team of the same name. We would ideally check for uniqueness at the organization level.

Start by locating the organizations model and the current team name uniqueness constraint. Verify the behavior with two organizations and same-named teams, then update the constraint so uniqueness is scoped to an organization and confirm that same-name teams across different organizations are accepted.

Written by the indexing model from the issue text.