Implement damage UI, damage and stale moves. (#45)

Reviewed-on: #45
Co-authored-by: Álex Román Núñez <eirexe@eirteam.moe>

src/ui/mod.rs

@@ -0,0 +1,18 @@
+use bevy::prelude::*;
+
+use crate::AppState;
+
+pub mod battle_ui;
+pub mod errors;
+pub mod fighter_info;
+
+#[derive(Default)]
+pub struct InGameUIPlugin;
+
+impl Plugin for InGameUIPlugin {
+    fn build(&self, app: &mut App) {
+        app.add_systems(OnEnter(AppState::InMatch), battle_ui::spawn_battle_ui)
+            .add_systems(OnExit(AppState::InMatch), battle_ui::cleanup_battle_ui)
+            .add_systems(PostUpdate, fighter_info::update_fighter_info_damage);
+    }
+}