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>

src/Meezi.Admin.API/Models/IntegrationDtos.cs

@@ -55,8 +55,11 @@ public record PlatformIntegrationsDto(
 public record UpdatePlatformIntegrationsRequest(
     string ActivePaymentGateway,
     IReadOnlyList<UpdatePaymentGatewayRequest> PaymentGateways,
-    UpdateKavenegarRequest Kavenegar,
-    UpdateAiIntegrationsRequest Ai);
+    // Optional: the admin UI no longer manages SMS (marketing SMS is
+    // bring-your-own-provider per café). When null, the stored platform
+    // Kavenegar config — still used for login OTPs — is left untouched.
+    UpdateKavenegarRequest? Kavenegar = null,
+    UpdateAiIntegrationsRequest? Ai = null);
 
 public record UpdateOpenAiIntegrationRequest(
     bool IsEnabled,