fix(playbook+flywheel): 修復 PlaybookSource enum + repair_steps 相容 + KM stats raw SQL

修復三個串聯 bug，讓 Playbook seed 能正常執行：

1. PlaybookSource 新增 YAML_RULE enum（alert_rules.yaml 匯入專用）
2. playbook_seed_service: source=YAML_RULE，dedup 改用 raw SQL by name，
   不再呼叫 list_playbooks（舊格式 repair_steps 會 validation error）
3. playbook_repository._orm_to_pydantic: 舊格式 repair_steps 補齊
   step_number/action_type 必填欄位（向下相容）
4. flywheel_stats_service: embedding IS NULL 改用 raw SQL，
   修復 KnowledgeEntryRecord ORM 無 embedding 屬性的 AttributeError

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

apps/api/src/repositories/playbook_repository.py

@@ -79,8 +79,24 @@ def _pydantic_to_orm(playbook: Playbook) -> PlaybookRecord:
     )
 
 
+def _normalize_repair_step(step: dict) -> dict:
+    """舊格式 repair_steps 補齊必填欄位（2026-04-15 ogt: 向下相容）"""
+    step = dict(step)
+    if "step_number" not in step:
+        step["step_number"] = 1
+    if "action_type" not in step:
+        cmd = step.get("command", "")
+        step["action_type"] = "kubectl" if cmd and not cmd.startswith("ssh") else "manual"
+    return step
+
+
 def _orm_to_pydantic(record: PlaybookRecord) -> Playbook:
     """PlaybookRecord ORM → Pydantic Playbook"""
+    raw_steps = record.repair_steps or []
+    normalized_steps = [
+        _normalize_repair_step(s) if isinstance(s, dict) else s
+        for s in raw_steps
+    ]
     return Playbook.model_validate({
         "playbook_id": record.playbook_id,
         "name": record.name,
@@ -88,7 +104,7 @@ def _orm_to_pydantic(record: PlaybookRecord) -> Playbook:
         "status": record.status,
         "source": record.source,
         "symptom_pattern": record.symptom_pattern,
-        "repair_steps": record.repair_steps,
+        "repair_steps": normalized_steps,
         "estimated_duration_minutes": record.estimated_duration_minutes,
         "source_incident_ids": record.source_incident_ids,
         "ai_confidence": float(record.ai_confidence),