Guard ethtool usage.

Services/Networking/NetworkService.qml

@@ -779,10 +779,13 @@ Singleton {
           root.activeEthernetDetails = details;
           root.activeEthernetDetailsTimestamp = Date.now();
           root.ethernetDetailsLoading = false;
-        } else {
+        } else if (ProgramCheckerService.ethtoolAvailable) {
           // Fallback to ethtool if sysfs unreadable or invalid
           ethernetEthtoolProcess.ifname = ethernetSysfsSpeedProcess.ifname;
           ethernetEthtoolProcess.running = true;
+        } else {
+          root.activeEthernetDetailsTimestamp = Date.now();
+          root.ethernetDetailsLoading = false;
         }
       }
     }

Services/System/ProgramCheckerService.qml

@@ -17,6 +17,7 @@ Singleton {
   property bool gnomeCalendarAvailable: false
   property bool pythonAvailable: false
   property bool wtypeAvailable: false
+  property bool ethtoolAvailable: false
 
   // Programs to check - maps property names to commands
   readonly property var programsToCheck: ({
@@ -25,7 +26,8 @@ Singleton {
                                             "wlsunsetAvailable": ["sh", "-c", "command -v wlsunset"],
                                             "gnomeCalendarAvailable": ["sh", "-c", "command -v gnome-calendar"],
                                             "wtypeAvailable": ["sh", "-c", "command -v wtype"],
-                                            "pythonAvailable": ["sh", "-c", "command -v python3"]
+                                            "pythonAvailable": ["sh", "-c", "command -v python3"],
+                                            "ethtoolAvailable": ["sh", "-c", "command -v ethtool"]
                                           })
 
   // Discord client auto-detection