feat: add copy user ID menu item and rename copy link to copy direct link

Add 'Copy user ID' button to both desktop and mobile post menus, allowing users to copy the full author address. This provides a way to verify authenticity against the 8-char display ID. Also rename 'Copy link' to 'Copy direct link' for clarity. Update security comments to reflect the new approach and add translations for all 35 languages.

public/translations/ko/default.json

@@ -99,7 +99,6 @@
   "interface": "인터페이스",
   "invalid_url": "잘못된 URL",
   "image_search": "이미지 검색",
-  "copy_link": "링크 복사",
   "hide_post": "게시물 숨기기",
   "hide_thread": "스레드 숨기기",
   "unhide_post": "게시물 숨기기 해제",
@@ -276,5 +275,7 @@
   "type": "Type",
   "yes": "Yes",
   "no": "No",
-  "pending_mod_approval": "Pending mod approval, not visible to users"
+  "pending_mod_approval": "Pending mod approval, not visible to users",
+  "copy_user_id": "사용자 ID 복사",
+  "copy_direct_link": "직접 링크 복사"
 }