feat(sms): bring-your-own-provider — cafés use their own SMS account

The platform no longer sells SMS. Each café saves its OWN Kavenegar API
key + sender line (new Cafes columns + migration) and campaigns are sent
and billed through that account.

Backend:
- GET/PUT /sms/settings (Manager/Owner; key echoed masked, verified
  against the provider before saving)
- campaign + balance use the café's credentials; SMS_NOT_CONFIGURED
  error when missing; plan-tier SMS gating removed everywhere
  (PlanLimitChecker, SmsMarketingService, billing status)
- platform Kavenegar config stays ONLY for login OTPs (env/DB)
- design-time DbContext factory so `dotnet ef migrations add` works
  without booting the host

Dashboard:
- SMS screen: provider-settings card, not-configured callout, campaign
  form disabled until configured; quota bar removed (usage stays as info)
- subscription screen + plan comparison no longer show SMS limits

Admin panel:
- Kavenegar/SMS section removed from integrations (request field now
  optional; stored OTP config untouched)
- SMS limit field removed from the plan editor
- nav label "درگاه و پیامک" → "درگاه پرداخت و AI"

fa/en/ar translations. 86 tests pass; all tsc clean.

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

web/dashboard/messages/ar.json

@@ -481,10 +481,36 @@
     "targetGroup": "المجموعة المستهدفة",
     "allCustomers": "كل العملاء",
     "send": "إرسال",
-    "usage": "الاستخدام هذا الشهر",
+    "usage": "المُرسَل هذا الشهر",
     "unlimited": "غير محدود",
     "sent": "تم الإرسال",
-    "failed": "فشل"
+    "failed": "فشل",
+    "charCount": "{count} حرفاً",
+    "smsPartsHint": "{parts} رسالة",
+    "balance": "رصيد حسابك",
+    "balanceAmount": "{amount} ريال",
+    "balanceNotConfigured": "خدمة SMS غير مفعّلة",
+    "sender": "خط الإرسال",
+    "recipientsCount": "{count} مستلماً",
+    "sendConfirm": "إرسال إلى {count} شخصاً؟",
+    "sending": "جارٍ الإرسال...",
+    "byoHint": "تُرسل الرسائل عبر حسابك وخطك الخاص — تُحتسب تكلفة الإرسال مباشرة لدى مزوّد SMS الخاص بك.",
+    "notConfiguredOwner": "لإرسال الرسائل، احفظ أولاً مفتاح API ورقم خط كاوه‌نگار في الإعدادات أعلاه.",
+    "notConfiguredStaff": "لم يقم مدير المقهى بإعداد خدمة SMS بعد.",
+    "settings": {
+      "title": "إعدادات مزوّد SMS",
+      "hint": "أنشئ مفتاح API من لوحة كاوه‌نگار (kavenegar.com) وأدخله مع رقم خط الإرسال.",
+      "apiKey": "مفتاح API",
+      "apiKeyPlaceholder": "API Key",
+      "senderNumber": "رقم خط الإرسال",
+      "senderPlaceholder": "10004346...",
+      "configured": "خدمة SMS مفعّلة.",
+      "notConfigured": "لم يتم الإعداد بعد.",
+      "save": "حفظ",
+      "saving": "جارٍ التحقق…",
+      "saved": "تم حفظ إعدادات SMS.",
+      "saveFailed": "مفتاح API غير صالح أو فشل الحفظ."
+    }
   },
   "reports": {
     "title": "التقارير والتحليلات",

web/dashboard/messages/en.json

@@ -500,19 +500,36 @@
     "targetGroup": "Target group",
     "allCustomers": "All customers",
     "send": "Send",
-    "usage": "Usage this month",
+    "usage": "Sent this month",
     "unlimited": "Unlimited",
     "sent": "Sent",
     "failed": "Failed",
     "charCount": "{count} chars",
     "smsPartsHint": "{parts} SMS",
-    "balance": "Account credit",
+    "balance": "Your account credit",
     "balanceAmount": "{amount} Rials",
-    "balanceNotConfigured": "Kavenegar not configured",
+    "balanceNotConfigured": "SMS service not set up",
     "sender": "Sender line",
     "recipientsCount": "{count} recipients",
     "sendConfirm": "Send to {count} people?",
-    "sending": "Sending..."
+    "sending": "Sending...",
+    "byoHint": "SMS is sent through your OWN provider account and line — sending costs are billed directly by your SMS provider.",
+    "notConfiguredOwner": "To send SMS, first save your Kavenegar API key and sender line in the settings above.",
+    "notConfiguredStaff": "The SMS service has not been set up by the café manager yet.",
+    "settings": {
+      "title": "SMS provider settings",
+      "hint": "Create an API key in your Kavenegar panel (kavenegar.com) and enter it with your sender line number.",
+      "apiKey": "Kavenegar API key",
+      "apiKeyPlaceholder": "API Key",
+      "senderNumber": "Sender line number",
+      "senderPlaceholder": "10004346...",
+      "configured": "SMS service is active.",
+      "notConfigured": "Not set up yet.",
+      "save": "Save",
+      "saving": "Verifying…",
+      "saved": "SMS settings saved.",
+      "saveFailed": "The API key is invalid or saving failed."
+    }
   },
   "reports": {
     "title": "Reports & analytics",

web/dashboard/messages/fa.json

@@ -500,19 +500,36 @@
     "targetGroup": "گروه هدف",
     "allCustomers": "همه مشتریان",
     "send": "ارسال",
-    "usage": "مصرف این ماه",
+    "usage": "ارسال‌شده این ماه",
     "unlimited": "نامحدود",
     "sent": "ارسال شد",
     "failed": "ناموفق",
     "charCount": "{count} حرف",
     "smsPartsHint": "{parts} پیامک",
-    "balance": "اعتبار حساب",
+    "balance": "اعتبار حساب شما",
     "balanceAmount": "{amount} ریال",
-    "balanceNotConfigured": "Kavenegar پیکربندی نشده",
+    "balanceNotConfigured": "سرویس پیامک راه‌اندازی نشده",
     "sender": "خط فرستنده",
     "recipientsCount": "{count} مخاطب",
     "sendConfirm": "ارسال به {count} نفر؟",
-    "sending": "در حال ارسال..."
+    "sending": "در حال ارسال...",
+    "byoHint": "پیامک با حساب و خط اختصاصی خود شما ارسال می‌شود — هزینه ارسال مستقیماً با اپراتور پیامک شماست.",
+    "notConfiguredOwner": "برای ارسال پیامک ابتدا کلید API و شماره خط کاوه‌نگار خود را در تنظیمات بالا ثبت کنید.",
+    "notConfiguredStaff": "سرویس پیامک هنوز توسط مدیر کافه راه‌اندازی نشده است.",
+    "settings": {
+      "title": "تنظیمات سرویس پیامک",
+      "hint": "از پنل کاوه‌نگار (kavenegar.com) کلید API بسازید و همراه شماره خط خود وارد کنید.",
+      "apiKey": "کلید API کاوه‌نگار",
+      "apiKeyPlaceholder": "API Key",
+      "senderNumber": "شماره خط ارسال",
+      "senderPlaceholder": "10004346...",
+      "configured": "سرویس پیامک فعال است.",
+      "notConfigured": "هنوز راه‌اندازی نشده.",
+      "save": "ذخیره",
+      "saving": "در حال بررسی…",
+      "saved": "تنظیمات پیامک ذخیره شد.",
+      "saveFailed": "کلید API نامعتبر است یا ذخیره ناموفق بود."
+    }
   },
   "reports": {
     "title": "گزارش‌ها و تحلیل",
@@ -1481,7 +1498,7 @@
       "title": "مدیریت سامانه",
       "dashboard": "داشبورد",
       "plans": "اشتراک و قیمت",
-      "integrations": "درگاه و پیامک",
+      "integrations": "درگاه پرداخت و AI",
       "notifications": "اعلان‌ها",
       "settings": "تنظیمات اپ",
       "features": "قابلیت‌ها",