feat(sprint5.1): Data Safety Guardrails 全鏈路整合 (L1-L5)

Layer 0 - K8s RBAC:
  - k8s/rbac/api-velero-reader.yaml: awoooi-executor SA Velero backup reader

Layer 1 - DB Migration (已在 188 執行):
  - M-002: approval_records 新增 approval_level/votes/required_votes
  - M-003: alert_event_type ENUM 新增 8 個值

Layer 2 - IaC:
  - ops/config/service-registry.yaml: 全服務 Stateful 分級清單 (BLOCK/CRITICAL_HITL/STANDARD_HITL/AUTO)

Layer 3 - Python Services:
  - service_registry.py: 讀取 YAML，提供 is_blocked/requires_multisig/get_required_votes
  - velero_client.py: kubectl 查詢 Velero 備份年齡，失敗 fallback 999h
  - preflight_service.py: Pre-flight 安全檢查 (Q2/Q4 決策)

Layer 1-M001 - Playbook model:
  - playbook.py: 新增 requires_approval_level/stateful_targets/requires_pre_backup

Layer 4 - 業務邏輯:
  - alert_operation_log_repository.py: 新增 8 個 event_type (Guardrail/Pre-flight/MultiSig/備份)
  - auto_repair_service.py: 注入 Service Registry Guardrail 檢查 (BLOCK → 直接拒絕)
  - webhooks.py: ALERT_RECEIVED 溯源記錄 + auto_repair flag Q9 + Langfuse trace_id Q10
  - db/models.py: ApprovalRecord 同步 approval_level/votes/required_votes 欄位
  - docker-health-monitor.sh: 純感知層改造（移除所有 docker restart 邏輯）

Layer 5 - Telegram 通知:
  - telegram_gateway.py: T1-T6 六個新通知方法 (Guardrail/Pre-flight/Backup/MultiSig/ChangeApplied)

參考: ADR-062 Data Safety Guardrails, ADR-063 Service Registry IaC

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

apps/api/src/db/models.py

@@ -124,6 +124,26 @@ class ApprovalRecord(Base):
         comment="Last time this alert pattern was seen",
     )
 
+    # Sprint 5.1 MultiSig 雙簽核支援 (2026-04-08 Claude Sonnet 4.6 Asia/Taipei，ADR-062 Q3)
+    approval_level: Mapped[str] = mapped_column(
+        String(20),
+        default="standard",
+        nullable=False,
+        comment="standard=1票審核, critical=2票MultiSig",
+    )
+    approval_votes: Mapped[list[dict[str, Any]]] = mapped_column(
+        JSON,
+        default=list,
+        nullable=False,
+        comment="[{user_id, voted_at, action}]",
+    )
+    required_votes: Mapped[int] = mapped_column(
+        Integer,
+        default=1,
+        nullable=False,
+        comment="standard=1, critical=2",
+    )
+
     # 2026-04-06 ogt: Phase 26 — 關聯 Incident ID
     # Playbook 萃取和 KM 寫入必須知道 incident_id，不能靠文字解析
     incident_id: Mapped[str | None] = mapped_column(