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/Program.cs

@@ -1,3 +1,5 @@
+using StellaOps.Cartographer.Options;
+
 var builder = WebApplication.CreateBuilder(args);
 
 builder.Configuration
@@ -7,10 +9,30 @@ builder.Configuration
 builder.Services.AddOptions();
 builder.Services.AddLogging();
 
+var authoritySection = builder.Configuration.GetSection("Cartographer:Authority");
+var authorityOptions = new CartographerAuthorityOptions();
+authoritySection.Bind(authorityOptions);
+CartographerAuthorityOptionsConfigurator.ApplyDefaults(authorityOptions);
+authorityOptions.Validate();
+
+builder.Services.AddSingleton(authorityOptions);
+builder.Services.AddOptions<CartographerAuthorityOptions>()
+    .Bind(authoritySection)
+    .PostConfigure(CartographerAuthorityOptionsConfigurator.ApplyDefaults);
+
 // TODO: register Cartographer graph builders, overlay workers, and Authority client once implementations land.
 
 var app = builder.Build();
 
+if (!authorityOptions.Enabled)
+{
+    app.Logger.LogWarning("Cartographer Authority authentication is disabled; enable it before production deployments.");
+}
+else if (authorityOptions.AllowAnonymousFallback)
+{
+    app.Logger.LogWarning("Cartographer Authority allows anonymous fallback; disable fallback before production rollout.");
+}
+
 app.MapGet("/healthz", () => Results.Ok(new { status = "ok" }));
 app.MapGet("/readyz", () => Results.Ok(new { status = "warming" }));