fix(ui): avoid int CommandParameter cast crash in usage monitor presets

RelayCommand<int> casts its object parameter directly rather than
converting it, so a string CommandParameter ("7"/"30") would throw
InvalidCastException at runtime. Split into two parameterless commands.

src/ClaudeDo.Ui/ViewModels/Modals/UsageMonitorModalViewModel.cs

@@ -89,6 +89,11 @@ public sealed partial class UsageMonitorModalViewModel : ViewModelBase
     }
 
     [RelayCommand]
+    private Task SetPreset7Days() => SetPreset(7);
+
+    [RelayCommand]
+    private Task SetPreset30Days() => SetPreset(30);
+
     private Task SetPreset(int days)
     {
         ApplyPresetRange(days);

src/ClaudeDo.Ui/Views/Modals/UsageMonitorModalView.axaml

@@ -92,9 +92,9 @@
       <StackPanel DockPanel.Dock="Top" Orientation="Horizontal" Spacing="8" Margin="20,12,20,0">
         <TextBlock Classes="meta" Text="{loc:Tr modals.usageMonitor.period}" VerticalAlignment="Center"/>
         <Button Classes="btn" Content="{loc:Tr modals.usageMonitor.last7Days}"
-                Command="{Binding SetPresetCommand}" CommandParameter="7"/>
+                Command="{Binding SetPreset7DaysCommand}"/>
         <Button Classes="btn" Content="{loc:Tr modals.usageMonitor.last30Days}"
-                Command="{Binding SetPresetCommand}" CommandParameter="30"/>
+                Command="{Binding SetPreset30DaysCommand}"/>
         <TextBlock Classes="meta" Text="{loc:Tr modals.usageMonitor.fromDate}" VerticalAlignment="Center"/>
         <ctl:ThemedDatePicker SelectedDate="{Binding StartDate}"/>
         <TextBlock Classes="meta" Text="{loc:Tr modals.usageMonitor.toDate}" VerticalAlignment="Center"/>

tests/ClaudeDo.Ui.Tests/ViewModels/UsageMonitorModalViewModelTests.cs

@@ -258,7 +258,7 @@ public class UsageMonitorModalViewModelTests
         await vm.LoadAsync();
         var callsAfterInitialLoad = worker.ModelUsageCalls;
 
-        await vm.SetPresetCommand.ExecuteAsync(30);
+        await vm.SetPreset30DaysCommand.ExecuteAsync(null);
 
         Assert.Equal(callsAfterInitialLoad + 1, worker.ModelUsageCalls);
         Assert.Equal(callsAfterInitialLoad + 1, worker.TaskUsageCalls);