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-Communication.md

@@ -59,6 +59,14 @@ Both central and site clusters. Each side has communication actors that handle m
 - Central sends an unsubscribe request when the debug view closes. The site removes its stream subscription.
 - The stream is session-based and temporary.
 
+### 6a. Debug Snapshot (Central → Site)
+- **Pattern**: Request/Response (one-shot, no subscription).
+- Central sends a `DebugSnapshotRequest` (identified by instance unique name) to the site.
+- Site's Deployment Manager routes to the Instance Actor by unique name.
+- Instance Actor builds and returns a `DebugViewSnapshot` with all current attribute values and alarm states (same payload as the streaming initial snapshot).
+- No subscription is created; no stream is established.
+- Uses the 30-second `QueryTimeout`.
+
 ### 7. Health Reporting (Site → Central)
 - **Pattern**: Periodic push.
 - Sites periodically send health metrics (connection status, node status, buffer depth, script error rates, alarm evaluation error rates) to central.
@@ -68,6 +76,7 @@ Both central and site clusters. Each side has communication actors that handle m
 - Central queries sites for:
   - Parked messages (store-and-forward dead letters).
   - Site event logs.
+  - Instance debug snapshots (attribute values and alarm states).
 - Central can also send management commands:
   - Retry or discard parked messages.