After delete, Livewire still re-renders the source change view (modal
$refresh / morph). Policy @can checks then call isAdminOfTeam() with a
null team_id and throw a TypeError (HTTP 500) before the redirect.
Guard null team_id in GitlabAppPolicy and GithubAppPolicy, clear the
Livewire model after delete, and skip @can when the model is gone.
GitlabAppPolicy previously allowed any authenticated user to update,
delete, and create GitLab sources. Align it with GithubAppPolicy, require
Application create authorization on the private-repo wizard, and reject
OAuth callbacks from non-admins so members cannot escalate privileges.
