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.Core/Entities/Cafe.cs

@@ -48,6 +48,12 @@ public class Cafe : BaseEntity
     public decimal DefaultTaxRate { get; set; } = 9m;
     public bool AllowBranchTaxOverride { get; set; }
 
+    /// <summary>Café's own Kavenegar API key — marketing SMS is bring-your-own-provider;
+    /// the platform does not sell SMS. Null = SMS not configured for this café.</summary>
+    public string? SmsApiKey { get; set; }
+    /// <summary>Café's own SMS sender line number (e.g. 10004346).</summary>
+    public string? SmsSenderNumber { get; set; }
+
     public ICollection<Branch> Branches { get; set; } = [];
     public ICollection<Table> Tables { get; set; } = [];
     public ICollection<Employee> Employees { get; set; } = [];

src/Meezi.Core/Interfaces/ISmsService.cs

@@ -20,4 +20,19 @@ public interface ISmsService
 
     /// <summary>Returns credit balance from the Kavenegar account, or null if not configured.</summary>
     Task<KavenegarAccountInfo?> GetAccountInfoAsync(CancellationToken cancellationToken = default);
+
+    /// <summary>
+    /// Bulk send using the CALLER's own provider credentials — marketing SMS is
+    /// bring-your-own-provider (each café configures its own API key + sender line).
+    /// Never throws — failures per batch are counted and returned.
+    /// </summary>
+    Task<BulkSendResult> SendBulkWithCredentialsAsync(
+        string apiKey,
+        string senderNumber,
+        IReadOnlyList<string> phones,
+        string message,
+        CancellationToken cancellationToken = default);
+
+    /// <summary>Credit balance for an EXPLICIT API key (a café's own account), or null on failure.</summary>
+    Task<KavenegarAccountInfo?> GetAccountInfoAsync(string apiKey, CancellationToken cancellationToken = default);
 }