fix(subscription): plan comparison + checkout read the live plan catalog

The merchant plan page hard-coded 4 tiers, prices and a feature matrix
that drifted from the admin-editable platform catalog (Starter tier
missing, stale prices/features). PlanComparison and CheckoutScreen now
consume /platform/plans + new /platform/features-catalog:

- columns = active plans by SortOrder (incl. Starter), names from
  DisplayNameFa/En, prices from MonthlyPriceToman
- limit rows from PlanLimitsData (int.MaxValue → "نامحدود")
- feature rows from the feature catalog, ticked via FeatureKeys
- checkout validates the ?plan= param against isBillableOnline and
  prices from the catalog — no more client-side price constants

fa/en/ar limit-row labels added.

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>

web/dashboard/messages/ar.json

@@ -1320,6 +1320,17 @@
         "Business": "أعمال",
         "Enterprise": "مؤسسات"
       },
+      "limits": {
+        "maxOrdersPerDay": "طلبات في اليوم",
+        "maxBranches": "الفروع",
+        "maxTerminals": "أجهزة الكاشير",
+        "maxTables": "الطاولات",
+        "maxCustomers": "عملاء CRM",
+        "maxSmsPerMonth": "رسائل SMS شهرياً",
+        "maxMenuItems": "أصناف القائمة",
+        "maxReportHistoryDays": "سجل التقارير (أيام)",
+        "maxMenuAi3dPerMonth": "صور AI ثلاثية الأبعاد شهرياً"
+      },
       "features": {
         "ordersPerDay": "طلبات يومياً",
         "terminals": "أجهزة نقطة البيع",

web/dashboard/messages/en.json

@@ -1402,6 +1402,17 @@
         "Business": "Business",
         "Enterprise": "Enterprise"
       },
+      "limits": {
+        "maxOrdersPerDay": "Orders per day",
+        "maxBranches": "Branches",
+        "maxTerminals": "POS terminals",
+        "maxTables": "Tables",
+        "maxCustomers": "CRM customers",
+        "maxSmsPerMonth": "SMS per month",
+        "maxMenuItems": "Menu items",
+        "maxReportHistoryDays": "Report history (days)",
+        "maxMenuAi3dPerMonth": "AI 3D images per month"
+      },
       "features": {
         "ordersPerDay": "Orders per day",
         "terminals": "POS terminals",

web/dashboard/messages/fa.json

@@ -1403,6 +1403,17 @@
         "Business": "بیزنس",
         "Enterprise": "سازمانی"
       },
+      "limits": {
+        "maxOrdersPerDay": "سفارش در روز",
+        "maxBranches": "شعبه",
+        "maxTerminals": "ترمینال صندوق",
+        "maxTables": "میز",
+        "maxCustomers": "مشتری CRM",
+        "maxSmsPerMonth": "پیامک در ماه",
+        "maxMenuItems": "آیتم منو",
+        "maxReportHistoryDays": "تاریخچه گزارش (روز)",
+        "maxMenuAi3dPerMonth": "تصویر AI سه‌بعدی در ماه"
+      },
       "features": {
         "ordersPerDay": "سفارش در روز",
         "terminals": "ترمینال صندوق",