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.

src/__Libraries/StellaOps.Microservice/StellaMicroserviceOptions.cs

@@ -0,0 +1,40 @@
+using StellaOps.Router.Common;
+
+namespace StellaOps.Microservice;
+
+/// <summary>
+/// Options for configuring a Stella microservice.
+/// </summary>
+public sealed class StellaMicroserviceOptions
+{
+    /// <summary>
+    /// Gets or sets the service name.
+    /// </summary>
+    public required string ServiceName { get; set; }
+
+    /// <summary>
+    /// Gets or sets the semantic version.
+    /// </summary>
+    public required string Version { get; set; }
+
+    /// <summary>
+    /// Gets or sets the region where this instance is deployed.
+    /// </summary>
+    public required string Region { get; set; }
+
+    /// <summary>
+    /// Gets or sets the unique instance identifier.
+    /// </summary>
+    public string InstanceId { get; set; } = Guid.NewGuid().ToString("N");
+
+    /// <summary>
+    /// Gets the router endpoints to connect to.
+    /// At least one router endpoint is required.
+    /// </summary>
+    public List<RouterEndpointConfig> Routers { get; set; } = [];
+
+    /// <summary>
+    /// Gets or sets the optional path to a YAML config file for endpoint overrides.
+    /// </summary>
+    public string? EndpointConfigPath { get; set; }
+}