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.

docs/examples/policies/serverless.yaml

@@ -5,6 +5,17 @@ metadata:
     - serverless
     - prod
     - strict
+exceptions:
+  effects:
+    - id: suppress-canary
+      name: Canary Freeze
+      effect: suppress
+      routingTemplate: secops-approvers
+      maxDurationDays: 14
+  routingTemplates:
+    - id: secops-approvers
+      authorityRouteId: governance.secops
+      requireMfa: true
 rules:
   - name: Block High And Above
     severity: [High, Critical]