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>

tests/Meezi.API.Tests/OtpNormalizerTests.cs

@@ -0,0 +1,27 @@
+using Meezi.Core.Utilities;
+using Xunit;
+
+namespace Meezi.API.Tests;
+
+public class OtpNormalizerTests
+{
+    [Theory]
+    [InlineData("916581", "916581")]
+    [InlineData(" 916581 ", "916581")]
+    [InlineData("۹۱۶۵۸۱", "916581")]
+    [InlineData("٩١٦٥٨١", "916581")]
+    public void Normalize_maps_to_ascii_digits(string input, string expected)
+    {
+        Assert.Equal(expected, OtpNormalizer.Normalize(input));
+        Assert.True(OtpNormalizer.IsValidSixDigitCode(input));
+    }
+
+    [Theory]
+    [InlineData("")]
+    [InlineData("12345")]
+    [InlineData("1234567")]
+    public void IsValid_rejects_invalid(string input)
+    {
+        Assert.False(OtpNormalizer.IsValidSixDigitCode(input));
+    }
+}