Add agent version to mcp node list

Thread the linker-injected version string into the Agent struct and
return it in the NodeStatus RPC. The CLI now dials each node and
displays the agent version alongside name and address.

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

internal/agent/nodestatus.go

@@ -31,6 +31,7 @@ func (a *Agent) NodeStatus(ctx context.Context, _ *mcpv1.NodeStatusRequest) (*mc
 		Runtime:        a.Config.Agent.ContainerRuntime,
 		ServiceCount:   uint32(len(services)), //nolint:gosec // bounded
 		ComponentCount: componentCount,
+		AgentVersion:   a.Version,
 	}
 
 	// Runtime version.