fix(phase26): 打通 Incident→DB→KM 完整鏈路 + namespace 修正

問題根因:
1. create_incident_for_approval 只存 Redis，不存 PostgreSQL
   → TTL 7天後消失，Playbook 萃取永遠找不到 Incident
2. ApprovalRecord 無 incident_id 欄位
   → _trigger_playbook_extraction 靠 regex 掃中文文字找 INC-，永遠失敗
3. operation_parser namespace fallback 是 "default"
   → 所有 deployment 在 awoooi-prod，203 次執行全失敗

修復:
- Incident 同時寫入 Redis + PostgreSQL (save_to_episodic_memory)
- ApprovalRecord 加入 incident_id 欄位 (model + ORM + migration)
- alertmanager_webhook 建立 Approval 後回寫 incident_id
- _trigger_playbook_extraction 直接用 approval.incident_id
- operation_parser DEFAULT_NAMESPACE = "awoooi-prod"

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

apps/api/src/db/models.py

@@ -124,6 +124,15 @@ class ApprovalRecord(Base):
         comment="Last time this alert pattern was seen",
     )
 
+    # 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(
+        String(64),
+        nullable=True,
+        index=True,
+        comment="Associated Incident ID (INC-YYYYMMDD-XXXXXX)",
+    )
+
     # Timestamps
     created_at: Mapped[datetime] = mapped_column(
         DateTime(timezone=True),