feat: Implement provisioning pipelines for subscription management

- Add ReactivatePipeline to handle subscription reactivation, including scaling Docker services, health verification, status updates, audit logging, and broadcasting status changes.
- Introduce RotateCredentialsPipeline for OAuth2 credential rotation, managing the deletion of old apps, creation of new ones, credential storage, access verification, and audit logging.
- Create StepRunner to manage job step execution, including lifecycle management and progress broadcasting via SignalR.
- Implement SuspendPipeline for subscription suspension, scaling down services, updating statuses, logging audits, and broadcasting changes.
- Add UpdateScreenLimitPipeline to update Xibo CMS screen limits and record snapshots.
- Introduce XiboFeatureManifests for hardcoded feature ACLs per role.
- Add docker-compose.dev.yml for local development with PostgreSQL setup.

OTSSignsOrchestrator.Desktop/Models/LiveStackItem.cs

@@ -22,4 +22,10 @@ public class LiveStackItem
 
     /// <summary>Label of the host — convenience property for data-binding.</summary>
     public string HostLabel => Host?.Label ?? string.Empty;
+
+    /// <summary>
+    /// Server-side customer ID. Populated when fleet data is loaded from the server API.
+    /// Null when loaded only from local Docker discovery.
+    /// </summary>
+    public Guid? CustomerId { get; set; }
 }