feat: Add new projects to solution and implement contract testing documentation

- Added "StellaOps.Policy.Engine", "StellaOps.Cartographer", and "StellaOps.SbomService" projects to the StellaOps solution.
- Created AGENTS.md to outline the Contract Testing Guild Charter, detailing mission, scope, and definition of done.
- Established TASKS.md for the Contract Testing Task Board, outlining tasks for Sprint 62 and Sprint 63 related to mock servers and replay testing.

src/StellaOps.TimelineIndexer/StellaOps.TimelineIndexer.Worker/Program.cs

@@ -0,0 +1,7 @@
+using StellaOps.TimelineIndexer.Worker;
+
+var builder = Host.CreateApplicationBuilder(args);
+builder.Services.AddHostedService<Worker>();
+
+var host = builder.Build();
+host.Run();