feat: color-code referral network nodes by subscription status

Add subscription status colors: green (paid active), blue (trial active),
red (paid expired), orange (trial expired). Extract NODE_COLORS constant
as single source of truth. Add SubscriptionStatus union type. Show status
badge in user detail panel. Add i18n for all 4 locales.

src/locales/en.json

@@ -1257,7 +1257,11 @@
         "topReferrer": "Top referrer (10+)",
         "campaignUser": "From campaign",
         "partnerCampaignEdge": "Partner → Campaign",
-        "campaignNode": "Ad campaign"
+        "campaignNode": "Ad campaign",
+        "paidActive": "Paid subscription",
+        "trialActive": "Trial",
+        "paidExpired": "Paid expired",
+        "trialExpired": "Trial expired"
       },
       "user": {
         "tgId": "TG ID",
@@ -1276,7 +1280,13 @@
         "source": "Source",
         "referredBy": "Referred by",
         "fromCampaign": "Campaign",
-        "organic": "Organic"
+        "organic": "Organic",
+        "subscriptionStatus": {
+          "trial_active": "Trial",
+          "paid_active": "Paid",
+          "trial_expired": "Trial expired",
+          "paid_expired": "Paid expired"
+        }
       },
       "campaign": {
         "startParam": "Parameter",

src/locales/fa.json

@@ -1091,7 +1091,11 @@
         "topReferrer": "ارجاع‌دهنده برتر (+۱۰)",
         "campaignUser": "از کمپین",
         "partnerCampaignEdge": "شریک → کمپین",
-        "campaignNode": "کمپین تبلیغاتی"
+        "campaignNode": "کمپین تبلیغاتی",
+        "paidActive": "اشتراک پرداختی",
+        "trialActive": "آزمایشی",
+        "paidExpired": "اشتراک پرداختی منقضی",
+        "trialExpired": "آزمایشی منقضی"
       },
       "user": {
         "tgId": "شناسه TG",
@@ -1110,7 +1114,13 @@
         "source": "منبع",
         "referredBy": "معرفی شده توسط",
         "fromCampaign": "کمپین",
-        "organic": "طبیعی"
+        "organic": "طبیعی",
+        "subscriptionStatus": {
+          "trial_active": "آزمایشی",
+          "paid_active": "پرداختی",
+          "trial_expired": "آزمایشی منقضی",
+          "paid_expired": "پرداختی منقضی"
+        }
       },
       "campaign": {
         "startParam": "پارامتر",

src/locales/ru.json

@@ -1278,7 +1278,11 @@
         "topReferrer": "Топ-реферер (10+)",
         "campaignUser": "Из кампании",
         "partnerCampaignEdge": "Партнёр → РК",
-        "campaignNode": "Рекламная кампания"
+        "campaignNode": "Рекламная кампания",
+        "paidActive": "Платная подписка",
+        "trialActive": "Триал",
+        "paidExpired": "Платная истекла",
+        "trialExpired": "Триал истёк"
       },
       "user": {
         "tgId": "TG ID",
@@ -1297,7 +1301,13 @@
         "source": "Источник",
         "referredBy": "Пришёл от",
         "fromCampaign": "РК",
-        "organic": "Органический"
+        "organic": "Органический",
+        "subscriptionStatus": {
+          "trial_active": "Триал",
+          "paid_active": "Платная",
+          "trial_expired": "Триал истёк",
+          "paid_expired": "Платная истекла"
+        }
       },
       "campaign": {
         "startParam": "Параметр",

src/locales/zh.json

@@ -1091,7 +1091,11 @@
         "topReferrer": "顶级推荐人 (10+)",
         "campaignUser": "来自活动",
         "partnerCampaignEdge": "合作伙伴 → 活动",
-        "campaignNode": "广告活动"
+        "campaignNode": "广告活动",
+        "paidActive": "付费订阅",
+        "trialActive": "试用",
+        "paidExpired": "付费已过期",
+        "trialExpired": "试用已过期"
       },
       "user": {
         "tgId": "TG ID",
@@ -1110,7 +1114,13 @@
         "source": "来源",
         "referredBy": "由...推荐",
         "fromCampaign": "活动",
-        "organic": "自然流量"
+        "organic": "自然流量",
+        "subscriptionStatus": {
+          "trial_active": "试用",
+          "paid_active": "付费",
+          "trial_expired": "试用已过期",
+          "paid_expired": "付费已过期"
+        }
       },
       "campaign": {
         "startParam": "参数",