Phase 3C: Deployment pipeline & Store-and-Forward engine

Deployment Manager (WP-1–8, WP-16):
- DeploymentService: full pipeline (flatten→validate→send→track→audit)
- OperationLockManager: per-instance concurrency control
- StateTransitionValidator: Enabled/Disabled/NotDeployed transition matrix
- ArtifactDeploymentService: broadcast to all sites with per-site results
- Deployment identity (GUID + revision hash), idempotency, staleness detection
- Instance lifecycle commands (disable/enable/delete) with deduplication

Store-and-Forward (WP-9–15):
- StoreAndForwardStorage: SQLite persistence, 3 categories, no max buffer
- StoreAndForwardService: fixed-interval retry, transient-only buffering, parking
- ReplicationService: async best-effort to standby (fire-and-forget)
- Parked message management (query/retry/discard from central)
- Messages survive instance deletion, S&F drains on disable

620 tests pass (+79 new), zero warnings.

src/ScadaLink.DeploymentManager/ServiceCollectionExtensions.cs

@@ -6,13 +6,16 @@ public static class ServiceCollectionExtensions
 {
     public static IServiceCollection AddDeploymentManager(this IServiceCollection services)
     {
-        // Phase 0: skeleton only
+        services.AddSingleton<OperationLockManager>();
+        services.AddScoped<IFlatteningPipeline, FlatteningPipeline>();
+        services.AddScoped<DeploymentService>();
+        services.AddScoped<ArtifactDeploymentService>();
         return services;
     }
 
     public static IServiceCollection AddDeploymentManagerActors(this IServiceCollection services)
     {
-        // Phase 0: placeholder for Akka actor registration
+        // Akka actor registration is handled by Host component during actor system startup
         return services;
     }
 }