fix: process GPN response in DiscoveringParametersState

The GPN response (ParameterInfoStruct list) was received but never
processed — organizeParameters() was never called, so discovered
parameters were lost and gpnStatus was never set to 'supported'.

Now on each successful GPN response:
- device.organizeParameters() is called to store leaf params/props
- device.setGpnStatus('supported') marks the device as GPN-capable

This fixes: parameters not showing in UI, wrong dataModel detection,
and PeriodicInformInterval not appearing after SPV.

Generated with [Continue](https://continue.dev)

Co-Authored-By: Continue <noreply@continue.dev>

app/services/cwmp/main_state_machine.ts

@@ -130,7 +130,21 @@ class DiscoveringParametersState extends DeviceState {
       return { nextState: new CriticalReadsState(), response: '' }
     }
 
-    // Process response and continue
+    // GPN success — process the response
+    if (context.message?.success && context.message.data) {
+      try {
+        context.device.organizeParameters(context.message.data, new Date())
+        context.device.setGpnStatus('supported')
+        logger.info(
+          { deviceId: context.device.identifier, paramCount: context.device.getParameters().length },
+          '[DiscoveringParameters] GPN response processed'
+        )
+      } catch (e: any) {
+        logger.error({ error: e?.message }, '[DiscoveringParameters] Error processing GPN response')
+      }
+    }
+
+    // Continue with next path in queue if any
     if (this.parameterQueue.length > 0) {
       return { response: await this.processNext(context) }
     }