Add unit tests for SBOM ingestion and transformation

- Implement `SbomIngestServiceCollectionExtensionsTests` to verify the SBOM ingestion pipeline exports snapshots correctly.
- Create `SbomIngestTransformerTests` to ensure the transformation produces expected nodes and edges, including deduplication of license nodes and normalization of timestamps.
- Add `SbomSnapshotExporterTests` to test the export functionality for manifest, adjacency, nodes, and edges.
- Introduce `VexOverlayTransformerTests` to validate the transformation of VEX nodes and edges.
- Set up project file for the test project with necessary dependencies and configurations.
- Include JSON fixture files for testing purposes.

src/Scheduler/__Tests/StellaOps.Scheduler.WebService.Tests/GraphJobEventPublisherTests.cs

@@ -56,10 +56,11 @@ public sealed class GraphJobEventPublisherTests
 
         await publisher.PublishAsync(notification, CancellationToken.None);
 
-        var message = Assert.Single(loggerProvider.Messages);
-        Assert.Contains("\"kind\":\"scheduler.graph.job.completed\"", message);
-        Assert.Contains("\"tenant\":\"tenant-alpha\"", message);
-        Assert.Contains("\"resultUri\":\"oras://result\"", message);
+        Assert.Contains(loggerProvider.Messages, message => message.Contains("unsupported driver", StringComparison.OrdinalIgnoreCase));
+        var eventPayload = loggerProvider.Messages.FirstOrDefault(message => message.Contains("\"kind\":\"scheduler.graph.job.completed\"", StringComparison.Ordinal));
+        Assert.NotNull(eventPayload);
+        Assert.Contains("\"tenant\":\"tenant-alpha\"", eventPayload);
+        Assert.Contains("\"resultUri\":\"oras://result\"", eventPayload);
     }
 
     [Fact]