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.

etc/authority.yaml.sample

@@ -129,7 +129,7 @@ clients:
     displayName: "AOC Verification Agent"
     grantTypes: [ "client_credentials" ]
     audiences: [ "api://concelier", "api://excitor" ]
-    scopes: [ "aoc:verify" ]
+    scopes: [ "aoc:verify", "advisory:read", "vex:read" ]
     tenant: "tenant-default"
     senderConstraint: "dpop"
     auth: