fix: rename "Regular user" to "No subscription" in legend

The gray color in the referral network legend represents users without
a subscription, not "regular/organic" users. Updated labels in all
4 locales (en, ru, fa, zh) to reflect this.

src/locales/ru.json

@@ -1274,7 +1274,7 @@
         "title": "Легенда",
         "fillTitle": "Подписка",
         "borderTitle": "Роль реферера",
-        "regularUser": "Обычный",
+        "regularUser": "Без подписки",
         "activeReferrer": "Активный реферер",
         "partner": "Партнёр",
         "topReferrer": "Топ-реферер (10+)",