feat: Implement Scheduler Worker Options and Planner Loop

- Added `SchedulerWorkerOptions` class to encapsulate configuration for the scheduler worker.
- Introduced `PlannerBackgroundService` to manage the planner loop, fetching and processing planning runs.
- Created `PlannerExecutionService` to handle the execution logic for planning runs, including impact targeting and run persistence.
- Developed `PlannerExecutionResult` and `PlannerExecutionStatus` to standardize execution outcomes.
- Implemented validation logic within `SchedulerWorkerOptions` to ensure proper configuration.
- Added documentation for the planner loop and impact targeting features.
- Established health check endpoints and authentication mechanisms for the Signals service.
- Created unit tests for the Signals API to ensure proper functionality and response handling.
- Configured options for authority integration and fallback authentication methods.

src/StellaOps.Cartographer.Tests/Options/CartographerAuthorityOptionsConfiguratorTests.cs

@@ -0,0 +1,51 @@
+using StellaOps.Auth.Abstractions;
+using StellaOps.Cartographer.Options;
+using Xunit;
+
+namespace StellaOps.Cartographer.Tests.Options;
+
+public class CartographerAuthorityOptionsConfiguratorTests
+{
+    [Fact]
+    public void ApplyDefaults_AddsGraphScopes()
+    {
+        var options = new CartographerAuthorityOptions();
+
+        CartographerAuthorityOptionsConfigurator.ApplyDefaults(options);
+
+        Assert.Contains(StellaOpsScopes.GraphRead, options.RequiredScopes);
+        Assert.Contains(StellaOpsScopes.GraphWrite, options.RequiredScopes);
+    }
+
+    [Fact]
+    public void ApplyDefaults_DoesNotDuplicateScopes()
+    {
+        var options = new CartographerAuthorityOptions();
+        options.RequiredScopes.Add("GRAPH:READ");
+        options.RequiredScopes.Add(StellaOpsScopes.GraphWrite);
+
+        CartographerAuthorityOptionsConfigurator.ApplyDefaults(options);
+
+        Assert.Equal(2, options.RequiredScopes.Count);
+    }
+
+    [Fact]
+    public void Validate_AllowsDisabledConfiguration()
+    {
+        var options = new CartographerAuthorityOptions();
+
+        options.Validate(); // should not throw when disabled
+    }
+
+    [Fact]
+    public void Validate_ThrowsForInvalidIssuer()
+    {
+        var options = new CartographerAuthorityOptions
+        {
+            Enabled = true,
+            Issuer = "invalid"
+        };
+
+        Assert.Throws<InvalidOperationException>(() => options.Validate());
+    }
+}