feat(l10n): add descriptions for notification subscription limits

- Add Arabic and English descriptions for breaking news, daily digest, and weekly roundup notification subscription limits
- Update app_ar.arb and app_en.arb files with new localization entries

Author: fulleni

lib/l10n/arb/app_ar.arb

@@ -2089,5 +2089,17 @@
   "userLimitsTitle": "حدود المستخدم",
   "@userLimitsTitle": {
     "description": "عنوان قسم حدود المستخدم القابل للتوسيع."
+  },
+  "notificationSubscriptionBreakingOnlyDescription": "حد الاشتراكات التي ترسل تنبيهات فورية للأخبار العاجلة للعناوين المطابقة.",
+  "@notificationSubscriptionBreakingOnlyDescription": {
+    "description": "وصف لحد اشتراك إشعارات الأخبار العاجلة."
+  },
+  "notificationSubscriptionDailyDigestDescription": "حد الاشتراكات التي ترسل ملخصًا يوميًا للعناوين المطابقة.",
+  "@notificationSubscriptionDailyDigestDescription": {
+    "description": "وصف لحد اشتراك إشعارات الملخص اليومي."
+  },
+  "notificationSubscriptionWeeklyRoundupDescription": "حد الاشتراكات التي ترسل ملخصًا أسبوعيًا للعناوين المطابقة.",
+  "@notificationSubscriptionWeeklyRoundupDescription": {
+    "description": "وصف لحد اشتراك إشعارات الحصاد الأسبوعي."
   }
 }

lib/l10n/arb/app_en.arb

@@ -2085,5 +2085,17 @@
   "userLimitsTitle": "User Limits",
   "@userLimitsTitle": {
     "description": "Title for the User Limits expansion tile."
+  },
+  "notificationSubscriptionBreakingOnlyDescription": "Limit for subscriptions that send immediate alerts for matching headlines.",
+  "@notificationSubscriptionBreakingOnlyDescription": {
+    "description": "Description for the breaking news notification subscription limit."
+  },
+  "notificationSubscriptionDailyDigestDescription": "Limit for subscriptions that send a daily summary of matching headlines.",
+  "@notificationSubscriptionDailyDigestDescription": {
+    "description": "Description for the daily digest notification subscription limit."
+  },
+  "notificationSubscriptionWeeklyRoundupDescription": "Limit for subscriptions that send a weekly summary of matching headlines.",
+  "@notificationSubscriptionWeeklyRoundupDescription": {
+    "description": "Description for the weekly roundup notification subscription limit."
   }
 }