List Owned Resources

Snapshot the rows the caller owns in team_id for the leave-team UI.

The frontend's :class:LeaveTeamModal calls this once before submitting :func:leave_team to render a per-resource picker. Resource types with zero owned rows are omitted.

Args: team_id: Team the caller intends to leave. auth: Authenticated user context.

Returns: :class:OwnedResourcesResponse containing is_sole_member (so the UI can route directly to the destructive sole-member-leave flow) and the per-resource picker payload.