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.Server/Data/Entities/Operator.cs

@@ -0,0 +1,18 @@
+namespace OTSSignsOrchestrator.Server.Data.Entities;
+
+public enum OperatorRole
+{
+    Admin,
+    Viewer
+}
+
+public class Operator
+{
+    public Guid Id { get; set; }
+    public string Email { get; set; } = string.Empty;
+    public string PasswordHash { get; set; } = string.Empty;
+    public OperatorRole Role { get; set; }
+    public DateTime CreatedAt { get; set; }
+
+    public ICollection<RefreshToken> RefreshTokens { get; set; } = [];
+}