fix(thermostat-server): notify subscribers when ActivePresetHandle changes

SetActivePreset() was calling delegate->SetActivePresetHandle() without
notifying the reporting engine, so active subscriptions never received
a Report Data message after a SetActivePresetRequest command. The new
value was silently applied on the device side (confirmed via a direct
read) but was invisible to subscribed controllers.

Add a call to MatterReportingAttributeChangeCallback() after a
successful SetActivePresetHandle() to mark the attribute dirty and
trigger a subscription report to all subscribers.

Author: lboue

src/app/clusters/thermostat-server/ThermostatClusterPresets.cpp

@@ -18,6 +18,7 @@
 #include "ThermostatClusterPresets.h"
 #include "ThermostatCluster.h"
 
+#include <app/reporting/reporting.h>
 #include <platform/internal/CHIPDeviceLayerInternal.h>
 
 using namespace chip;
@@ -316,6 +317,10 @@ Status ThermostatAttrAccess::SetActivePreset(EndpointId endpoint, DataModel::Nul
         return StatusIB(err).mStatus;
     }
 
+    // Notify subscribers that ActivePresetHandle has changed so that they
+    // receive a subscription report with the new value.
+    MatterReportingAttributeChangeCallback(endpoint, Thermostat::Id, ActivePresetHandle::Id);
+
     return Status::Success;
 }