FIX(app): restore su - ubuntu -c for proper env and PATH

- su ubuntu -c may not set env vars properly
- Change to su - ubuntu -c to use login shell environment
- Projects path is hardcoded to /home/ubuntu/Projects

deploy/k8s/overlays/prod/kustomization.yaml

@@ -16,5 +16,5 @@ commonLabels:
 # 이미지 태그 설정 (ArgoCD Image Updater가 자동으로 업데이트)
 images:
   - name: gitea0213.kro.kr/bluemayne/mas
-    newTag: main-sha-878bf6866a72be3fd2f7064c8bcda96097093f40
+    newTag: main-sha-b8e84c1b6bc380490e4b313459ee02f438e3c125