Restructure solution layout by module

src/Signals/StellaOps.Signals/Services/ICallgraphIngestionService.cs

@@ -0,0 +1,16 @@
+using System.Threading;
+using System.Threading.Tasks;
+using StellaOps.Signals.Models;
+
+namespace StellaOps.Signals.Services;
+
+/// <summary>
+/// Handles ingestion of callgraph artifacts.
+/// </summary>
+public interface ICallgraphIngestionService
+{
+    /// <summary>
+    /// Ingests the supplied callgraph request.
+    /// </summary>
+    Task<CallgraphIngestResponse> IngestAsync(CallgraphIngestRequest request, CancellationToken cancellationToken);
+}