make level list scrollable

src/main.rs

@@ -46,6 +46,7 @@ impl eframe::App for PipeDash {
         ctx.set_pixels_per_point(2f32);
 
         egui::SidePanel::left("level_picker").default_width(100f32).show(ctx, |ui| {
+            egui::ScrollArea::vertical().show(ui, |ui| {
                 ui.with_layout(egui::Layout::top_down_justified(egui::Align::Min), |ui| {
                     for (idx, level) in self.level_list.iter().enumerate() {
                         if ui.selectable_label(self.selected_level == Some(idx), level.display_name()).clicked() {
@@ -54,6 +55,8 @@ impl eframe::App for PipeDash {
                     }
                 })
             });
+        });
+
         egui::CentralPanel::default().show(ctx, |ui| {
             ui.vertical_centered_justified(|ui| {
                 ui.horizontal_top(|ui| {