[AZ-1126] Migrate capturedAt to DateTimeOffset

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

SatelliteProvider.Api/Validators/UavTileMetadataValidator.cs

@@ -54,9 +54,9 @@ public sealed class UavTileMetadataValidator : AbstractValidator<UavTileMetadata
         // time per call (rule executes at validation time, not constructor
         // time). Equivalent to AZ-488 Rule 4 in UavTileQualityGate.
         RuleFor(m => m.CapturedAt)
-            .Must(capturedAt => capturedAt.ToUniversalTime() <= tp.GetUtcNow().UtcDateTime.AddSeconds(futureSkewSeconds))
+            .Must(capturedAt => capturedAt.UtcDateTime <= tp.GetUtcNow().UtcDateTime.AddSeconds(futureSkewSeconds))
                 .WithMessage($"`capturedAt` must be within {futureSkewSeconds}s of the current time (no future-dated tiles).")
-            .Must(capturedAt => capturedAt.ToUniversalTime() >= tp.GetUtcNow().UtcDateTime.AddDays(-maxAgeDays))
+            .Must(capturedAt => capturedAt.UtcDateTime >= tp.GetUtcNow().UtcDateTime.AddDays(-maxAgeDays))
                 .WithMessage($"`capturedAt` must be within the last {maxAgeDays} days.");
 
         // `FlightId` is intentionally not validated beyond JSON shape — AZ-503

SatelliteProvider.Api/Validators/UavUploadValidationFilter.cs

@@ -73,11 +73,12 @@ public sealed class UavUploadValidationFilter : IEndpointFilter
         {
             payload = JsonSerializer.Deserialize<UavTileBatchMetadataPayload>(metadataField, _jsonOptions);
         }
-        catch (JsonException)
+        catch (JsonException ex)
         {
+            var message = string.IsNullOrWhiteSpace(ex.Message) ? MetadataJsonParseError : ex.Message;
             return Results.ValidationProblem(new Dictionary<string, string[]>
             {
-                [MetadataField] = new[] { MetadataJsonParseError },
+                [MetadataField] = new[] { message },
             });
         }