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.API/Services/PlanLimitChecker.cs

@@ -114,26 +114,9 @@ public class PlanLimitChecker : IPlanLimitChecker
             }
         }
 
-        var smsCampaignPath = $"/api/cafes/{cafeId}/sms/campaign";
-        if (path.Equals(smsCampaignPath, StringComparison.OrdinalIgnoreCase) ||
-            path.Equals($"{smsCampaignPath}/", StringComparison.OrdinalIgnoreCase))
-        {
-            var limitsSms = await _platformCatalog.GetLimitsAsync(tier, cancellationToken);
-            var maxSms = limitsSms.MaxSmsPerMonth;
-            if (maxSms == 0)
-                return (false, "PLAN_LIMIT_REACHED", "SMS is not available on the Free plan. Please upgrade.");
-
-            if (maxSms == int.MaxValue)
-                return (true, null, null);
-
-            var monthKey = $"sms:usage:{cafeId}:{DateTime.UtcNow:yyyy-MM}";
-            var redis = _redis.GetDatabase();
-            var used = await redis.StringGetAsync(monthKey);
-            var usedCount = used.HasValue ? (int)used : 0;
-
-            if (usedCount >= maxSms)
-                return (false, "PLAN_LIMIT_REACHED", "Monthly SMS limit reached for your plan. Please upgrade.");
-        }
+        // NOTE: SMS is deliberately NOT plan-gated — marketing SMS is
+        // bring-your-own-provider (the café's own API key + sender line), so the
+        // café's provider account is the only limit.
 
         return (true, null, null);
     }