FIX(app): fully apply jaejadle structure

- Remove vault path references
- Remove duplicate namespace.yaml, serviceaccount.yaml
- Integrate serviceaccount into base
- Fix Kustomize build

deploy/k8s/overlays/prod/kustomization.yaml

@@ -5,11 +5,8 @@ namespace: mas
 
 resources:
   - ../../base
-  - namespace.yaml
   - resourcequota.yaml
   - externalsecret.yaml
-  - serviceaccount.yaml
-  - ../../../vault/mas-postgres.yaml
 
 commonLabels:
   environment: production
@@ -17,5 +14,5 @@ commonLabels:
 # 이미지 태그 설정 (ArgoCD Image Updater가 자동으로 업데이트)
 images:
   - name: gitea0213.kro.kr/bluemayne/mas
-    newTag: main-sha-ea42d1b2e4dcaea223cf4dbdbc6eaa315ee1eeef
+    newTag: main-sha-e9a2e6b6eb654c38c415e9250635016b5b413ff9