feat: show blocked_count in broadcast admin UI

- Add blocked_count to Broadcast interface
- 4-column stats grid with blocked card (warning color)
- Show blocked count in broadcast list when > 0
- Fetch single broadcast by ID instead of listing all
- Add i18n keys for blocked/blockedShort in ru/en/zh/fa

src/locales/en.json

@@ -1196,6 +1196,8 @@
       "total": "Total",
       "sent": "Sent",
       "failed": "Failed",
+      "blocked": "Blocked",
+      "blockedShort": "blocked",
       "filter": "Filter",
       "message": "Message",
       "unknownAdmin": "Unknown",

src/locales/fa.json

@@ -917,6 +917,8 @@
       "total": "کل",
       "sent": "ارسال شده",
       "failed": "ناموفق",
+      "blocked": "مسدود شده",
+      "blockedShort": "مسدود",
       "filter": "فیلتر",
       "message": "پیام",
       "unknownAdmin": "نامعلوم",

src/locales/ru.json

@@ -1221,6 +1221,8 @@
       "total": "Всего",
       "sent": "Отправлено",
       "failed": "Ошибки",
+      "blocked": "Заблокировали",
+      "blockedShort": "заблок.",
       "filter": "Фильтр",
       "message": "Сообщение",
       "unknownAdmin": "Неизвестный админ",

src/locales/zh.json

@@ -969,6 +969,8 @@
       "total": "总计",
       "sent": "已发送",
       "failed": "失败",
+      "blocked": "已屏蔽",
+      "blockedShort": "屏蔽",
       "filter": "筛选",
       "message": "消息",
       "unknownAdmin": "未知",