feat(wave5-p2): GovernanceAgent 4 項自檢 + Ollama 健康告警規則 + Prometheus metrics 整合

MASTER plan_complete_v3.md Wave 5 P2.2 + P2.3 完成（multiple engineers 在限額前完成代碼，補 commit）：

P2.2 — GovernanceAgent 4 項自檢:
- governance_agent.py (342 行) — 每 1 小時自檢循環:
  · trust_drift（信任度漂移檢測）
  · knowledge_degradation（知識退化檢測）
  · llm_hallucination（LLM 幻覺檢測）
  · execution_blast_radius（執行爆炸半徑檢測）
- main.py lifespan: asyncio.create_task(run_governance_loop()) 啟動
  try/except 包裹，schedule 失敗不阻斷主流程
- failover_alerter.py: alert_governance(event_type, payload) 1h dedup
  四類事件 → Telegram MarkdownV2 告警

P2.3 — Ollama 健康規則 + Prometheus Metrics:
- ops/monitoring/ollama_health_rules.yaml (148 行):
  · OllamaHealthDegraded / OllamaPrimaryDown
  · OllamaFailoverTriggered / GeminiQuotaExceeded
  · 補 Prometheus 取資料的 alert rules
- core/metrics.py (57 行):
  · GEMINI_DAILY_CALL_COUNT / GEMINI_DAILY_QUOTA Gauge
  · OLLAMA_FAILOVER_TRIGGERED_TOTAL Counter
  · OLLAMA_CURRENT_PRIMARY_IS_OLLAMA Gauge
- ollama_failover_manager.py:
  · _check_gemini_quota: 每次 check 同步更新 Gauge（讓 Prometheus 取最新值）
  · select_provider: failover 時 inc Counter + 切 Primary Gauge
  · try/except 包裹，metric 失敗不阻斷主路由

E2E 測試:
- test_failover_e2e_dispatch.py (365 行)
  完整 dispatch 路徑：health check → failover decide → alerter → metrics

Tests: 54 passed (e2e_dispatch + failover_manager + failover_alerter)

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>
Co-Authored-By: Multiple Engineers (上 session Wave 5) <noreply@anthropic.com>

apps/api/src/main.py

@@ -546,6 +546,15 @@ async def lifespan(_app: FastAPI) -> AsyncGenerator[None, None]:
     except Exception as e:
         logger.warning("ai_slo_watchdog_schedule_failed", error=str(e))
 
+    # 2026-04-26 P2.2 by Claude — GovernanceAgent 4 項自檢（每 1 小時）
+    # MASTER P2.2：trust_drift / knowledge_degradation / llm_hallucination / execution_blast_radius
+    try:
+        from src.services.governance_agent import run_governance_loop
+        asyncio.create_task(run_governance_loop())
+        logger.info("governance_agent_scheduled", interval_sec=3600)
+    except Exception as e:
+        logger.warning("governance_agent_schedule_failed", error=str(e))
+
     # 2026-04-25 P1.2 by Claude Engineer-A2 — failover 整合到 ai_router + lifespan
     # OllamaFailoverManager + OllamaAutoRecoveryService 飛輪接線：
     #   failover 切換時 → recovery_callback → set_current_primary → Redis 持久化