fix: remove unused variables and field

lib/screens/cli_screen.dart

@@ -129,19 +129,19 @@ class _CLIScreenState extends State<CLIScreen> {
     // Parse data formats (matching Python example)
     if (packet.data.length >= 4) {
       try {
-        final valueU32 = packet.value32BitUnsigned;
-        final valueS32 = packet.value32BitSigned;
-        final valueU16 = packet.value16BitUnsigned;
-        final valueS16 = packet.value16BitSigned;
+        // valueU32 = packet.value32BitUnsigned;
+        // valueS32 = packet.value32BitSigned;
+        // valueU16 = packet.value16BitUnsigned;
+        // valueS16 = packet.value16BitSigned;
         
         // Commented out like in Python example
         // _addLogLine('         → 32-bit unsigned: ${valueU32.toString().padLeft(10)} | 32-bit signed: ${valueS32.toString().padLeft(10)}');
         // _addLogLine('         → 16-bit unsigned: ${valueU16.toString().padLeft(10)} | 16-bit signed: ${valueS16.toString().padLeft(10)}');
         
-        if (valueU32 != null && valueU32 > 0) {
-          final floatVal = valueU32 / 100.0;
+        // if (valueU32 != null && valueU32 > 0) {
+        //   final floatVal = valueU32 / 100.0;
         //   _addLogLine('         → As float (÷100): ${floatVal.toStringAsFixed(2).padLeft(12)}');
-        }
+        // }
       } catch (e) {
         _addLogLine('         → Parse error: $e');
       }

lib/services/ble_service.dart

@@ -24,7 +24,6 @@ class BLEService extends ChangeNotifier {
   final List<DataPacket> _dataPackets = [];
   int _packetCount = 0;
   DateTime? _startTime;
-  DateTime? _lastDataTime;
   
   // Getters
   bool get isConnected => _isConnected;
@@ -399,7 +398,6 @@ class BLEService extends ChangeNotifier {
   // Handle received data
   void _onDataReceived(List<int> data) {
     _packetCount++;
-    _lastDataTime = DateTime.now();
     
     final packet = DataPacket(
       data: List.from(data),
@@ -512,7 +510,6 @@ class BLEService extends ChangeNotifier {
     _dataPackets.clear();
     _packetCount = 0;
     _startTime = null;
-    _lastDataTime = null;
     notifyListeners();
   }