Add active filter count display and improve UI in ScannerScreen

- Introduced a new method `_getActiveFilterCount` to calculate the number of active filters.
- Updated the filter button to show a badge with the active filter count.
- Changed the clear filter button icon for better clarity.
- Enhanced the hint style in the scan filter widget for improved visibility.

example/lib/home/scanner_screen.dart

@@ -255,6 +255,15 @@ class _ScannerScreenState extends State<ScannerScreen> {
     if (mounted) await _startScan();
   }
 
+  int _getActiveFilterCount(ScanFilter? filter) {
+    if (filter == null) return 0;
+    int n = 0;
+    if (filter.withServices.isNotEmpty) n++;
+    if (filter.withNamePrefix.isNotEmpty) n++;
+    if (filter.withManufacturerData.isNotEmpty) n++;
+    return n;
+  }
+
   void _showScanFilterBottomSheet() {
     showModalBottomSheet(
       isScrollControlled: true,
@@ -657,32 +666,42 @@ class _ScannerScreenState extends State<ScannerScreen> {
                   ),
                 ),
                 const SizedBox(width: 4),
-                TextButton.icon(
+                Badge(
-                  onPressed: _showScanFilterBottomSheet,
+                  isLabelVisible: _getActiveFilterCount(scanFilter) > 0,
-                  icon: Icon(
-                    scanFilter != null
-                        ? Icons.filter_list
-                        : Icons.filter_list_outlined,
-                    size: 18,
-                    color: scanFilter != null
-                        ? colorScheme.primary
-                        : colorScheme.onSurface,
-                  ),
                   label: Text(
-                    'Filter',
+                    '${_getActiveFilterCount(scanFilter)}',
-                    style: TextStyle(
+                    style: const TextStyle(
-                      color: scanFilter != null
+                      fontSize: 10,
-                          ? colorScheme.primary
-                          : colorScheme.onSurface,
-                      fontSize: 12,
                       fontWeight: FontWeight.w600,
                     ),
                   ),
-                  style: TextButton.styleFrom(
+                  child: TextButton.icon(
-                    padding: EdgeInsets.symmetric(horizontal: 8),
+                    onPressed: _showScanFilterBottomSheet,
-                    backgroundColor: scanFilter != null
+                    icon: Icon(
-                        ? colorScheme.primaryContainer
+                      scanFilter != null
-                        : null,
+                          ? Icons.filter_list
+                          : Icons.filter_list_outlined,
+                      size: 18,
+                      color: scanFilter != null
+                          ? colorScheme.primary
+                          : colorScheme.onSurface,
+                    ),
+                    label: Text(
+                      'Filter',
+                      style: TextStyle(
+                        color: scanFilter != null
+                            ? colorScheme.primary
+                            : colorScheme.onSurface,
+                        fontSize: 12,
+                        fontWeight: FontWeight.w600,
+                      ),
+                    ),
+                    style: TextButton.styleFrom(
+                      padding: EdgeInsets.symmetric(horizontal: 8),
+                      backgroundColor: scanFilter != null
+                          ? colorScheme.primaryContainer
+                          : null,
+                    ),
                   ),
                 ),
                 const Spacer(),

example/lib/home/widgets/scan_filter_widget.dart

@@ -239,7 +239,7 @@ class _ScanFilterWidgetState extends State<ScanFilterWidget> {
                       flex: 2,
                       child: OutlinedButton.icon(
                         onPressed: clearFilter,
-                        icon: const Icon(Icons.clear_all),
+                        icon: const Icon(Icons.clear),
                         label: const Text('Clear All'),
                         style: OutlinedButton.styleFrom(
                           foregroundColor: colorScheme.onSurface,
@@ -328,6 +328,9 @@ class _ScanFilterWidgetState extends State<ScanFilterWidget> {
               style: const TextStyle(fontFamily: 'monospace'),
               decoration: InputDecoration(
                 hintText: hintText,
+                hintStyle: TextStyle(
+                  color: colorScheme.onSurface.withValues(alpha: 0.15),
+                ),
                 helperText: helperText,
                 helperMaxLines: 2,
                 helperStyle: TextStyle(