feat(AIOps): 全開 P1-P6 feature flags + Nemotron + offline replay loop

- configmap: 啟用 AIOPS_P1~P6 全部總開關與子開關
- configmap: ENABLE_NEMOTRON_COLLABORATION=true（回歸 120s timeout）
- feature_flags.py: 補齊 AIOPS_P6_GOVERNANCE_ENABLED 缺失欄位
- main.py: 掛載 run_offline_replay_loop（ADR-087 Phase 6）

2026-04-15 ogt + Claude Sonnet 4.6（亞太）

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

apps/api/src/core/feature_flags.py

@@ -173,6 +173,10 @@ class AIOpsFeatureFlags(BaseSettings):
         default=False,
         description="P6: Playbook trust 分布漂移偵測是否啟用",
     )
+    AIOPS_P6_GOVERNANCE_ENABLED: bool = Field(
+        default=False,
+        description="P6: 治理閉環總開關（offline_replay_service / model_rollback_service 守衛）",
+    )
 
     def is_phase_enabled(self, phase: int) -> bool:
         """