[AZ-1126] Migrate capturedAt to DateTimeOffset

Co-authored-by: Cursor <cursoragent@cursor.com>

SatelliteProvider.Common/DTO/UavTileMetadata.cs

@@ -1,10 +1,11 @@
 using System.Text.Json.Serialization;
+using SatelliteProvider.Common.Json;
 
 namespace SatelliteProvider.Common.DTO;
 
-// AZ-488 / `uav-tile-upload.md` v1.0.0 — per-tile metadata supplied with each
-// batch item. `CapturedAt` is normalized to UTC by the upload handler before
-// reaching the persistence layer.
+// AZ-488 / `uav-tile-upload.md` — per-tile metadata supplied with each batch
+// item. `CapturedAt` is UTC-aware (`DateTimeOffset`) and normalized to UTC
+// before persistence (AZ-1126 / F-AZ810-2).
 //
 // AZ-503: `FlightId` is optional. When provided, two UAVs uploading the same
 // (z, x, y) cell from different flights coexist as distinct DB rows and write
@@ -27,7 +28,8 @@ public record UavTileMetadata
     [JsonRequired]
     public double TileSizeMeters { get; init; }
     [JsonRequired]
-    public DateTime CapturedAt { get; init; }
+    [JsonConverter(typeof(UtcOffsetRequiredDateTimeOffsetConverter))]
+    public DateTimeOffset CapturedAt { get; init; }
     public Guid? FlightId { get; init; }
 }