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/__Libraries/StellaOps.Scheduler.Queue/SchedulerQueueMetrics.cs

@@ -1,3 +1,4 @@
+using System;
 using System.Collections.Concurrent;
 using System.Collections.Generic;
 using System.Diagnostics.Metrics;
@@ -5,7 +6,7 @@ using System.Linq;
 
 namespace StellaOps.Scheduler.Queue;
 
-internal static class SchedulerQueueMetrics
+public static class SchedulerQueueMetrics
 {
     private const string TransportTagName = "transport";
     private const string QueueTagName = "queue";
@@ -21,6 +22,25 @@ internal static class SchedulerQueueMetrics
         "scheduler_queue_depth",
         ObserveDepth);
 
+    public static IReadOnlyList<SchedulerQueueDepthSample> CaptureDepthSamples()
+    {
+        var snapshot = DepthSamples.ToArray();
+        if (snapshot.Length == 0)
+        {
+            return Array.Empty<SchedulerQueueDepthSample>();
+        }
+
+        var samples = new SchedulerQueueDepthSample[snapshot.Length];
+        for (var i = 0; i < snapshot.Length; i++)
+        {
+            var entry = snapshot[i];
+            samples[i] = new SchedulerQueueDepthSample(entry.Key.transport, entry.Key.queue, entry.Value);
+        }
+
+        Array.Sort(samples, SchedulerQueueDepthSampleComparer.Instance);
+        return Array.AsReadOnly(samples);
+    }
+
     public static void RecordEnqueued(string transport, string queue)
         => EnqueuedCounter.Add(1, BuildTags(transport, queue));
 
@@ -45,6 +65,22 @@ internal static class SchedulerQueueMetrics
     internal static IReadOnlyDictionary<(string transport, string queue), long> SnapshotDepths()
         => DepthSamples.ToDictionary(pair => pair.Key, pair => pair.Value);
 
+    private sealed class SchedulerQueueDepthSampleComparer : IComparer<SchedulerQueueDepthSample>
+    {
+        public static SchedulerQueueDepthSampleComparer Instance { get; } = new();
+
+        public int Compare(SchedulerQueueDepthSample x, SchedulerQueueDepthSample y)
+        {
+            var transport = string.Compare(x.Transport, y.Transport, StringComparison.Ordinal);
+            if (transport != 0)
+            {
+                return transport;
+            }
+
+            return string.Compare(x.Queue, y.Queue, StringComparison.Ordinal);
+        }
+    }
+
     private static KeyValuePair<string, object?>[] BuildTags(string transport, string queue)
         => new[]
         {
@@ -63,3 +99,5 @@ internal static class SchedulerQueueMetrics
         }
     }
 }
+
+public readonly record struct SchedulerQueueDepthSample(string Transport, string Queue, long Depth);