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);
+    }
+}

tests/StellaOps.Microservice.Tests/StellaOps.Microservice.Tests.csproj

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+<Project Sdk="Microsoft.NET.Sdk">
+  <PropertyGroup>
+    <TargetFramework>net10.0</TargetFramework>
+    <LangVersion>preview</LangVersion>
+    <Nullable>enable</Nullable>
+    <ImplicitUsings>enable</ImplicitUsings>
+    <TreatWarningsAsErrors>true</TreatWarningsAsErrors>
+    <IsPackable>false</IsPackable>
+  </PropertyGroup>
+  <ItemGroup>
+    <PackageReference Include="Microsoft.NET.Test.Sdk" Version="17.12.0" />
+    <PackageReference Include="xunit" Version="2.9.2" />
+    <PackageReference Include="xunit.runner.visualstudio" Version="3.0.1">
+      <IncludeAssets>runtime; build; native; contentfiles; analyzers; buildtransitive</IncludeAssets>
+      <PrivateAssets>all</PrivateAssets>
+    </PackageReference>
+    <PackageReference Include="coverlet.collector" Version="6.0.4">
+      <IncludeAssets>runtime; build; native; contentfiles; analyzers; buildtransitive</IncludeAssets>
+      <PrivateAssets>all</PrivateAssets>
+    </PackageReference>
+  </ItemGroup>
+  <ItemGroup>
+    <ProjectReference Include="..\..\src\__Libraries\StellaOps.Microservice\StellaOps.Microservice.csproj" />
+  </ItemGroup>
+</Project>