feat(api): .NET 10 multi-tenant REST API

Full backend implementation:
- Multi-tenant cafe/restaurant management (menus, orders, tables, staff)
- POS order flow with ZarinPal and Snappfood payment integration
- OTP authentication via Kavenegar SMS
- QR digital menu with public discover/finder endpoints
- Customer loyalty, coupons, CRM
- PostgreSQL via EF Core, Redis for caching/sessions
- Background jobs, webhook handlers
- Full migration history

Co-Authored-By: Claude Sonnet 4.5 <noreply@anthropic.com>

src/Meezi.API/Services/RefreshTokenStore.cs

@@ -0,0 +1,54 @@
+using System.Text.Json;
+using StackExchange.Redis;
+
+namespace Meezi.API.Services;
+
+public record RefreshTokenPayload(
+    string UserId,
+    string CafeId,
+    string Role,
+    string PlanTier,
+    string Language,
+    string Actor = Meezi.Core.Constants.MeeziActorKinds.Merchant);
+
+public interface IRefreshTokenStore
+{
+    Task StoreAsync(string refreshToken, RefreshTokenPayload payload, TimeSpan ttl, CancellationToken cancellationToken = default);
+    Task<RefreshTokenPayload?> GetAsync(string refreshToken, CancellationToken cancellationToken = default);
+    Task RevokeAsync(string refreshToken, CancellationToken cancellationToken = default);
+}
+
+public class RedisRefreshTokenStore : IRefreshTokenStore
+{
+    private readonly IConnectionMultiplexer _redis;
+
+    public RedisRefreshTokenStore(IConnectionMultiplexer redis)
+    {
+        _redis = redis;
+    }
+
+    private static string Key(string token) => $"refresh:{token}";
+
+    public async Task StoreAsync(string refreshToken, RefreshTokenPayload payload, TimeSpan ttl, CancellationToken cancellationToken = default)
+    {
+        var db = _redis.GetDatabase();
+        var json = JsonSerializer.Serialize(payload);
+        await db.StringSetAsync(Key(refreshToken), json, ttl);
+    }
+
+    public async Task<RefreshTokenPayload?> GetAsync(string refreshToken, CancellationToken cancellationToken = default)
+    {
+        var db = _redis.GetDatabase();
+        var value = await db.StringGetAsync(Key(refreshToken));
+        if (value.IsNullOrEmpty)
+            return null;
+
+        return JsonSerializer.Deserialize<RefreshTokenPayload>(value.ToString());
+    }
+
+    public async Task RevokeAsync(string refreshToken, CancellationToken cancellationToken = default)
+    {
+        var db = _redis.GetDatabase();
+        await db.KeyDeleteAsync(Key(refreshToken));
+    }
+}