feat(frontend): add confirmation dialog before deleting users, peers, and interfaces (#654)

* feat(frontend): add confirmation dialog before deleting users, peers, and interfaces (#652)

Add a browser confirm() dialog to the delete functions in UserEditModal,
PeerEditModal, and InterfaceEditModal to prevent accidental deletions.
The bulk-delete actions in UserView already had this protection; this
change brings single-item deletion in line with that behavior.

Translation keys (confirm-delete) added for all 10 supported locales:
de, en, es, fr, ko, pt, ru, uk, vi, zh.

Signed-off-by: LeC-D <leo.openc@gmail.com>

* fix broken translation files

---------

Signed-off-by: LeC-D <leo.openc@gmail.com>
Co-authored-by: Christoph Haas <christoph.h@sprinternet.at>

frontend/src/lang/translations/ko.json

@@ -282,6 +282,7 @@
           "label": "관리자 여부"
         }
       },
+      "confirm-delete": "사용자 '{id}'를 삭제하시겠습니까?",
       "interface-view": {
         "headline": "인터페이스 구성:"
       },
@@ -393,7 +394,8 @@
             "placeholder": "영구 Keepalive (0 = 기본값)"
           }
         },
-        "button-apply-defaults": "피어 기본값 적용"
+        "button-apply-defaults": "피어 기본값 적용",
+        "confirm-delete": "인터페이스 '{id}'를 삭제하시겠습니까?"
       },
       "peer-view": {
         "headline-peer": "피어:",
@@ -509,7 +511,8 @@
         },
         "expires-at": {
           "label": "만료 날짜"
-        }
+        },
+        "confirm-delete": "피어 '{id}'를 삭제하시겠습니까?"
       },
       "peer-multi-create": {
         "headline-peer": "여러 피어 생성",