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/en.json

@@ -1253,7 +1253,7 @@
         "title": "Legend",
         "fillTitle": "Subscription",
         "borderTitle": "Referral role",
-        "regularUser": "Regular user",
+        "regularUser": "No subscription",
         "activeReferrer": "Active referrer",
         "partner": "Partner",
         "topReferrer": "Top referrer (10+)",

src/locales/fa.json

@@ -1087,7 +1087,7 @@
         "title": "راهنما",
         "fillTitle": "اشتراک",
         "borderTitle": "نقش ارجاع‌دهنده",
-        "regularUser": "کاربر عادی",
+        "regularUser": "بدون اشتراک",
         "activeReferrer": "ارجاع‌دهنده فعال",
         "partner": "شریک",
         "topReferrer": "ارجاع‌دهنده برتر (+۱۰)",

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+)",

src/locales/zh.json

@@ -1087,7 +1087,7 @@
         "title": "图例",
         "fillTitle": "订阅状态",
         "borderTitle": "推荐角色",
-        "regularUser": "普通用户",
+        "regularUser": "无订阅",
         "activeReferrer": "活跃推荐人",
         "partner": "合作伙伴",
         "topReferrer": "顶级推荐人 (10+)",