feat(k8s): enable Signal Worker (Phase 8 go-live)

Enable Signal Worker to process Redis Streams signals
and trigger Incident Engine for alert aggregation.

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

k8s/awoooi-prod/08-deployment-worker.yaml

@@ -17,8 +17,8 @@ metadata:
     environment: prod
     component: signal-processor
 spec:
-  # 暫時設為 0，Worker 模組尚未完整 (Phase 6.5 待完善)
-  replicas: 0
+  # Phase 8: Worker 啟用 - 處理 Redis Streams 訊號
+  replicas: 1
   selector:
     matchLabels:
       app: awoooi-worker