fix(test): align governance self_failure assertions with nested payload schema

Codex commits dedb1208 + b710f3f3 (governance enrich + normalize) 把
_alert("governance_self_failure", ...) 的 payload structure 重構成嵌套：
  {status, impact: {failed_checks, total_checks, errors}, remediation, actionable}
（governance_agent.py:604-624，2026-04-29 critic M6 修），
但 3 個 test 還用舊路徑 `payload["total_checks"]` 直讀，KeyError 後 RuntimeError 模擬 cascading 失敗。

修法：3 個 assertion 改為讀正確嵌套路徑：
- test_governance_agent.py:601 → payload["impact"]["total_checks"|"failed_checks"]
- test_wave8_remaining_blockers.py:223 → 同
- test_wave8_remaining_blockers.py:268 → 同

Tests: 30 passed (test_governance_agent + test_wave8_remaining_blockers 全部)

效果：解開 dedb1208 / b710f3f3 / a38d9112 三個 commit 因 governance test fail
被擋在 build-and-deploy 之前的卡點，恢復 CD 鏈通暢。

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

apps/api/tests/test_governance_agent.py

@@ -619,9 +619,11 @@ class TestRunSelfCheckGlobalFailureAlert:
         governance_failure_calls = [c for c in calls if c[0][0] == "governance_self_failure"]
         assert len(governance_failure_calls) >= 1
 
+        # 2026-05-03 Claude Opus 4.7 + 統帥 ogt：對齊 governance_agent.py:604-624 的嵌套 payload structure
+        # （critic M6 修：{status, impact, remediation, actionable}），原本直接讀 payload["total_checks"] 會 KeyError
         payload = governance_failure_calls[0][0][1]
-        assert payload["total_checks"] == 5
-        assert len(payload["failed_checks"]) == 5
+        assert payload["impact"]["total_checks"] == 5
+        assert len(payload["impact"]["failed_checks"]) == 5
 
     @pytest.mark.asyncio
     async def test_two_checks_fail_does_not_trigger_governance_self_failure(self):

apps/api/tests/test_wave8_remaining_blockers.py

@@ -240,9 +240,10 @@ class TestB8GovernanceFailureAlert:
         agent._alert.assert_awaited_once()
         call_args = agent._alert.await_args
         assert call_args[0][0] == "governance_self_failure"
+        # 2026-05-03 Claude Opus 4.7 + 統帥 ogt：對齊 governance_agent.py:604-624 嵌套 payload structure
         payload = call_args[0][1]
-        assert payload["total_checks"] == 5
-        assert len(payload["failed_checks"]) >= 3
+        assert payload["impact"]["total_checks"] == 5
+        assert len(payload["impact"]["failed_checks"]) >= 3
 
     @pytest.mark.asyncio
     async def test_two_failures_no_alert(self):
@@ -282,5 +283,6 @@ class TestB8GovernanceFailureAlert:
         await agent.run_self_check()
 
         agent._alert.assert_awaited_once()
+        # 2026-05-03 Claude Opus 4.7 + 統帥 ogt：對齊 governance_agent.py:604-624 嵌套 payload structure
         payload = agent._alert.await_args[0][1]
-        assert len(payload["failed_checks"]) == 5
+        assert len(payload["impact"]["failed_checks"]) == 5