feat: partner-campaign integration in admin UI

- Add partner badge to campaigns list
- Add partner selector dropdown in campaign edit
- Support ?partnerId= query param in campaign create (replaces separate page)
- Filter already-assigned campaigns in partner assign flow
- Show taken campaigns greyed out with partner name
- Delete AdminPartnerCampaignCreate (replaced by query param approach)
- Add partner translations (ru, en, zh, fa)

src/locales/ru.json

@@ -2267,7 +2267,11 @@
         "active": "Активна",
         "cancel": "Отмена",
         "save": "Сохранить",
-        "saving": "Сохранение..."
+        "saving": "Сохранение...",
+        "partner": "Партнёр",
+        "noPartner": "Без партнёра",
+        "selectPartner": "Выберите партнёра",
+        "partnerAutoAssign": "Кампания будет автоматически привязана к партнёру {{name}}"
       },
       "stats": {
         "title": "Статистика кампании",