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/ja/default.json

@@ -99,7 +99,6 @@
   "interface": "インターフェース",
   "invalid_url": "無効なURL",
   "image_search": "画像検索",
-  "copy_link": "リンクをコピー",
   "hide_post": "投稿を非表示",
   "hide_thread": "スレッドを非表示",
   "unhide_post": "投稿を表示",
@@ -276,5 +275,7 @@
   "type": "タイプ",
   "yes": "はい",
   "no": "いいえ",
-  "pending_mod_approval": "モデレーターの承認待ち、ユーザーには表示されません"
+  "pending_mod_approval": "モデレーターの承認待ち、ユーザーには表示されません",
+  "copy_user_id": "ユーザーIDをコピー",
+  "copy_direct_link": "直接リンクをコピー"
 }