fix(gateway): thread agent_team through all 27 lifecycle Context sites

Arms the team-match spec gate that sat in its permissive fallback since
shipping: cell-scoped roles are now rejected on cross-team verbs at the
gateway (a misrouted frontend PM blocked, escalated, and held a backend
task live 2026-07-02). Org-wide roles remain exempt via the policy-side
_ORG_WIDE_ROLES. Test mocks aligned to carry consistent teams.

tests/unit/gateway/test_choreographer_impl_branches.py

@@ -632,6 +632,7 @@ async def test_delegate_parent_no_project_rejected() -> None:
     parent = MagicMock(
         status="in_progress",
         assigned_to=pm_id,
+        team="backend",
         project_id=None,
         product_id=None,
         title="p",