🐛 fix(telemetry): normalize timestamp kind

- set server timestamp as UTC with unspecified kind
- use unspecified kind for dto before persian conversion
- avoid timezone and kind issues in persian date conversion

src/GreenHome.Infrastructure/Services/Telemetry/TelemetryService.cs

@@ -38,11 +38,13 @@ public sealed class TelemetryService : ITelemetryService
                 entity.DeviceId = device.Id;
         }
 
-        entity.ServerTimestampUtc = DateTime.Now;
+        entity.ServerTimestampUtc = DateTime.SpecifyKind(DateTime.UtcNow, DateTimeKind.Unspecified);
 
         if (dto.TimestampUtc.HasValue)
         {
-            var (year, month, day, persianDate) = dto.TimestampUtc.Value.ToPersianDate();
+            var ts = DateTime.SpecifyKind(dto.TimestampUtc.Value, DateTimeKind.Unspecified);
+            entity.TimestampUtc = ts;
+            var (year, month, day, persianDate) = ts.ToPersianDate();
             entity.PersianYear = year;
             entity.PersianMonth = month;
             entity.PersianDate = persianDate;