feat(etl): add MapOrdinal and date validation with sentinel to JdeDateTransformer

- Add DefaultInvalidDateSentinel (1900-01-01) for invalid date handling
- Add optional invalidDateSentinel constructor parameter
- Add MapOrdinal override returning -1 for computed DateTime column
- Add GetDataTypeName override returning "datetime" for computed column
- Update ParseJdeDateTime with comprehensive validation:
  - Validate date is positive
  - Validate century (0 or 1)
  - Validate year (0-99)
  - Validate day of year (1-366 and respects leap year)
  - Validate time components (hours 0-23, minutes/seconds 0-59)
- Add tests for all new functionality

NEW/tests/JdeScoping.DataSync.Tests/Etl/Transformers/JdeDateTransformerTests.cs

@@ -80,6 +80,166 @@ public class JdeDateTransformerTests
         Assert.Equal(new DateTime(1999, 6, 15, 0, 0, 0), JdeDateTransformer.ParseJdeDateTime(99166m, 0m));
     }
 
+    [Fact]
+    public void MapOrdinal_DateOutputColumn_ReturnsNegativeOne()
+    {
+        // Arrange
+        var transformer = new JdeDateTransformer("UPMJ", "TDAY", "UpdatedAt");
+        var source = CreateMockReader(new[] { "UPMJ", "TDAY", "Other" }, new object[] { 124001m, 120000m, "Test" });
+        transformer.Transform(source);
+
+        // Act - ordinal 0 is the computed DateTime column (UPMJ becomes UpdatedAt at position 0)
+        var result = transformer.MapOrdinal(0, source);
+
+        // Assert - computed columns return -1
+        Assert.Equal(-1, result);
+    }
+
+    [Fact]
+    public void MapOrdinal_NonComputedColumn_ReturnsSourceOrdinal()
+    {
+        // Arrange
+        var transformer = new JdeDateTransformer("UPMJ", "TDAY", "UpdatedAt");
+        var source = CreateMockReader(new[] { "UPMJ", "TDAY", "Other" }, new object[] { 124001m, 120000m, "Test" });
+        transformer.Transform(source);
+
+        // Act - ordinal 1 is "Other" which maps to source ordinal 2
+        var result = transformer.MapOrdinal(1, source);
+
+        // Assert
+        Assert.Equal(2, result);
+    }
+
+    [Fact]
+    public void ParseJdeDateTime_InvalidDate_ReturnsSentinel()
+    {
+        // Arrange
+        var sentinel = new DateTime(1900, 1, 1);
+
+        // Act - 999999 is invalid (century 9 doesn't exist)
+        var result = JdeDateTransformer.ParseJdeDateTime(999999m, 0m, sentinel);
+
+        // Assert
+        Assert.Equal(sentinel, result);
+    }
+
+    [Fact]
+    public void ParseJdeDateTime_ZeroDate_ReturnsSentinel()
+    {
+        // Arrange
+        var sentinel = new DateTime(1900, 1, 1);
+
+        // Act
+        var result = JdeDateTransformer.ParseJdeDateTime(0m, 0m, sentinel);
+
+        // Assert
+        Assert.Equal(sentinel, result);
+    }
+
+    [Fact]
+    public void DefaultInvalidDateSentinel_Is1900()
+    {
+        // Assert
+        Assert.Equal(new DateTime(1900, 1, 1), JdeDateTransformer.DefaultInvalidDateSentinel);
+    }
+
+    [Fact]
+    public void GetDataTypeName_DateOutputColumn_ReturnsDatetime()
+    {
+        // Arrange
+        var transformer = new JdeDateTransformer("UPMJ", "TDAY", "UpdatedAt");
+        var source = CreateMockReader(new[] { "UPMJ", "TDAY", "Other" }, new object[] { 124001m, 120000m, "Test" });
+        source.GetDataTypeName(2).Returns("nvarchar");
+        var reader = transformer.Transform(source);
+
+        // Act - ordinal 0 is the computed DateTime column
+        var result = reader.GetDataTypeName(0);
+
+        // Assert
+        Assert.Equal("datetime", result);
+    }
+
+    [Fact]
+    public void GetDataTypeName_NonComputedColumn_DelegatesToSource()
+    {
+        // Arrange
+        var transformer = new JdeDateTransformer("UPMJ", "TDAY", "UpdatedAt");
+        var source = CreateMockReader(new[] { "UPMJ", "TDAY", "Other" }, new object[] { 124001m, 120000m, "Test" });
+        source.GetDataTypeName(2).Returns("nvarchar");
+        var reader = transformer.Transform(source);
+
+        // Act - ordinal 1 is "Other" which maps to source ordinal 2
+        var result = reader.GetDataTypeName(1);
+
+        // Assert
+        Assert.Equal("nvarchar", result);
+    }
+
+    [Fact]
+    public void ParseJdeDateTime_NegativeDate_ReturnsSentinel()
+    {
+        // Arrange
+        var sentinel = new DateTime(1900, 1, 1);
+
+        // Act
+        var result = JdeDateTransformer.ParseJdeDateTime(-100m, 0m, sentinel);
+
+        // Assert
+        Assert.Equal(sentinel, result);
+    }
+
+    [Fact]
+    public void ParseJdeDateTime_InvalidDayOfYear_ReturnsSentinel()
+    {
+        // Arrange
+        var sentinel = new DateTime(1900, 1, 1);
+
+        // Act - Day 400 doesn't exist
+        var result = JdeDateTransformer.ParseJdeDateTime(124400m, 0m, sentinel);
+
+        // Assert
+        Assert.Equal(sentinel, result);
+    }
+
+    [Fact]
+    public void ParseJdeDateTime_InvalidTime_ReturnsSentinel()
+    {
+        // Arrange
+        var sentinel = new DateTime(1900, 1, 1);
+
+        // Act - Hour 25 doesn't exist
+        var result = JdeDateTransformer.ParseJdeDateTime(124001m, 250000m, sentinel);
+
+        // Assert
+        Assert.Equal(sentinel, result);
+    }
+
+    [Fact]
+    public void ParseJdeDateTime_LeapYearDay366_ReturnsValidDate()
+    {
+        // Arrange
+        var sentinel = new DateTime(1900, 1, 1);
+
+        // Act - 2024 is a leap year, day 366 is valid
+        var result = JdeDateTransformer.ParseJdeDateTime(124366m, 0m, sentinel);
+
+        // Assert - December 31, 2024
+        Assert.Equal(new DateTime(2024, 12, 31), result);
+    }
+
+    [Fact]
+    public void ParseJdeDateTime_NonLeapYearDay366_ReturnsSentinel()
+    {
+        // Arrange
+        var sentinel = new DateTime(1900, 1, 1);
+
+        // Act - 2023 is NOT a leap year, day 366 is invalid
+        var result = JdeDateTransformer.ParseJdeDateTime(123366m, 0m, sentinel);
+
+        // Assert
+        Assert.Equal(sentinel, result);
+    }
+
     private static IDataReader CreateMockReader(string[] columns, object[] values)
     {
         var reader = Substitute.For<IDataReader>();