fix: avoid GPN on root path Device. which returns the full parameter tree

Two complementary fixes:
- IdleState: skip root-level parent paths (Device., InternetGatewayDevice.)
  when building the GPN queue. Params like Device.RootDataModelVersion have
  Device. as parent but sending GPN on Device. with NextLevel=0 returns the
  entire TR-181 tree in one response (potentially several MB).
  These root-level params are classified via deeper subtree GPN or catalog.
- task_queue: use NextLevel=1 for root paths (1 segment) as a safety net,
  NextLevel=0 for deeper paths to get all leaves of that subtree.

app/services/cwmp/task_queue.ts

@@ -40,7 +40,12 @@ export enum TaskStatus {
 export class CWMPTaskQueue extends EventEmitter {
   static task_map: Record<string, (props: any) => string> = {
     get_parameter_names: (parameterPath: string) => {
-      return CWMPMessageBuilder.getParameterNames(undefined, parameterPath, false)
+      // Use NextLevel=1 for root paths (e.g. "Device." or "InternetGatewayDevice.")
+      // to avoid fetching the entire parameter tree in a single response.
+      // For deeper paths (e.g. "Device.DeviceInfo.") use NextLevel=0 to get all leaves.
+      const segments = parameterPath.replace(/\.$/, '').split('.')
+      const nextLevel = segments.length <= 1
+      return CWMPMessageBuilder.getParameterNames(undefined, parameterPath, nextLevel)
     },
     get_parameter_attributes: (parameterNames: string[]) => {
       return CWMPMessageBuilder.getParameterAttributes(undefined, parameterNames)