fix(signoz_webhook): AIBlastRadius → BlastRadius 型別轉換

blast_radius 欄位傳入 AIBlastRadius 物件導致 Pydantic validation error，
approval 無法存進 DB（Telegram 仍送出但無法批准）。

修法：明確轉換 AIBlastRadius → BlastRadius，data_impact enum 用 .value 橋接。

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

apps/api/src/api/v1/signoz_webhook.py

@@ -313,16 +313,28 @@ async def create_signoz_approval(
             action = f"[AI 建議] {analysis_result.action_title}"
         else:
             action = f"SignOz Alert: {alert_name}"
-        approval_request = ApprovalRequestCreate(
-            action=action,
-            description=description,
-            risk_level=analysis_result.risk_level if analysis_result else risk_level,
-            blast_radius=analysis_result.blast_radius if analysis_result else BlastRadius(
+        # 轉換 AIBlastRadius → BlastRadius (兩者欄位相同，enum 型別不同)
+        if analysis_result and analysis_result.blast_radius:
+            ai_br = analysis_result.blast_radius
+            blast_radius = BlastRadius(
+                affected_pods=ai_br.affected_pods,
+                estimated_downtime=ai_br.estimated_downtime,
+                related_services=ai_br.related_services,
+                data_impact=DataImpact(ai_br.data_impact.value),
+            )
+        else:
+            blast_radius = BlastRadius(
                 affected_pods=1,
                 estimated_downtime="0",
                 related_services=[service_name],
                 data_impact=DataImpact.READ_ONLY,
-            ),
+            )
+
+        approval_request = ApprovalRequestCreate(
+            action=action,
+            description=description,
+            risk_level=analysis_result.risk_level if analysis_result else risk_level,
+            blast_radius=blast_radius,
             kubectl_command=command,
             dry_run_checks=[],
             requested_by="signoz-webhook",