feat: add CLI debug snapshot command for one-shot instance state inspection

Adds `debug snapshot --id <int>` to query a running instance's current
attribute values and alarm states without the subscribe/stream overhead
of the debug view. Routes through ManagementActor → CommunicationService
→ site DeploymentManager → InstanceActor using the existing remote query
pattern.

Component-SiteRuntime.md

@@ -75,6 +75,10 @@ Deployment Manager Singleton (Cluster Singleton)
 - **Enable**: Creates a new Instance Actor from the stored configuration (same as startup).
 - **Delete**: Stops the Instance Actor and its children, removes the deployed configuration from local SQLite. Does **not** clear store-and-forward messages.
 
+### Debug Snapshot Routing
+- Receives `DebugSnapshotRequest` from the Communication Layer and forwards to the Instance Actor by unique name (same lookup as `SubscribeDebugViewRequest`).
+- Returns an error response if no Instance Actor exists for the requested unique name (instance not deployed or not enabled).
+
 ---
 
 ## Instance Actor
@@ -110,6 +114,7 @@ Deployment Manager Singleton (Cluster Singleton)
 ### Debug View Support
 - On request from central (via Communication Layer), the Instance Actor provides a **snapshot** of all current attribute values and alarm states.
 - Subsequent changes are delivered via the site-wide Akka stream, filtered by instance unique name.
+- The Instance Actor also handles one-shot `DebugSnapshotRequest` messages: it builds the same snapshot (attribute values and alarm states) and replies directly to the sender. Unlike `SubscribeDebugViewRequest`, no subscriber is registered and no stream is established.
 
 ### Supervision Strategy