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);