Add signal contracts for reachability, exploitability, trust, and unknown symbols

- Introduced `ReachabilityState`, `RuntimeHit`, `ExploitabilitySignal`, `ReachabilitySignal`, `SignalEnvelope`, `SignalType`, `TrustSignal`, and `UnknownSymbolSignal` records to define various signal types and their properties.
- Implemented JSON serialization attributes for proper data interchange.
- Created project files for the new signal contracts library and corresponding test projects.
- Added deterministic test fixtures for micro-interaction testing.
- Included cryptographic keys for secure operations with cosign.

tests/StellaOps.Microservice.Tests/StellaMicroserviceOptionsTests.cs

@@ -0,0 +1,43 @@
+using StellaOps.Microservice;
+using StellaOps.Router.Common;
+using Xunit;
+
+namespace StellaOps.Microservice.Tests;
+
+public class StellaMicroserviceOptionsTests
+{
+    [Fact]
+    public void StellaMicroserviceOptions_CanBeCreated()
+    {
+        // Arrange & Act
+        var options = new StellaMicroserviceOptions
+        {
+            ServiceName = "test-service",
+            Version = "1.0.0",
+            Region = "eu1"
+        };
+
+        // Assert
+        Assert.Equal("test-service", options.ServiceName);
+        Assert.Equal("1.0.0", options.Version);
+        Assert.Equal("eu1", options.Region);
+        Assert.NotEmpty(options.InstanceId);
+    }
+
+    [Fact]
+    public void RouterEndpointConfig_CanBeCreated()
+    {
+        // Arrange & Act
+        var config = new RouterEndpointConfig
+        {
+            Host = "localhost",
+            Port = 5000,
+            TransportType = TransportType.Tcp
+        };
+
+        // Assert
+        Assert.Equal("localhost", config.Host);
+        Assert.Equal(5000, config.Port);
+        Assert.Equal(TransportType.Tcp, config.TransportType);
+    }
+}