feat: add referral code support to phone verification form

src/FrontOffice.Main/Shared/PhoneVerifyForm.razor.cs

@@ -29,6 +29,10 @@ public partial class PhoneVerifyForm
     [Parameter] public string? PhoneNumber { get; set; }
     [Parameter] public int ResendRemaining { get; set; }
 
+    // ── Referral ──
+    [Parameter] public string? ReferralCode { get; set; }
+    [Parameter] public EventCallback<string?> ReferralCodeChanged { get; set; }
+
     // ── Verify actions ──
     [Parameter] public EventCallback OnChangePhone { get; set; }
     [Parameter] public EventCallback OnResendOtp { get; set; }