Pause menu functionality (#89)

* make menu use actual soundsettings values
* allow changing volume in pause menu
* persist saving settings

crates/hedz_reloaded/src/client/mod.rs

@@ -33,6 +33,7 @@ pub mod debug;
 pub mod enemy;
 pub mod heal_effect;
 pub mod player;
+mod settings;
 pub mod setup;
 pub mod steam;
 pub mod ui;
@@ -49,6 +50,7 @@ pub fn plugin(app: &mut App) {
         audio::plugin,
         steam::plugin,
         ui::plugin,
+        settings::plugin,
     ));
 
     app.add_systems(