feat(ui): wire high score into game lifecycle and display

Add check_high_score system on GameEnter, insert HighScore resource
loaded from disk at startup, display best score on Start Menu and
Game Over screens.

src/game_state.rs

@@ -1,7 +1,9 @@
 use bevy::prelude::*;
 
-use crate::components::{Bullet, Enemy, EnemyBullet, GameOverUI, RestartMessage, StartButton, StartMenuUI};
+use crate::components::{
-use crate::resources::RestartPressed;
+    Bullet, Enemy, EnemyBullet, GameOverUI, HighScoreText, RestartMessage, StartButton, StartMenuUI,
+};
+use crate::resources::{HighScore, RestartPressed, Score};
 
 #[derive(Clone, Eq, PartialEq, Debug, Hash, Default, States)]
 pub enum AppState {
@@ -16,7 +18,7 @@ const BUTTON_HOVER: Color = Color::srgb(0.2, 0.2, 0.7);
 
 // --- Game Over UI ---
 
-pub fn setup_game_over_ui(mut commands: Commands) {
+pub fn setup_game_over_ui(mut commands: Commands, high_score: Res<HighScore>, score: Res<Score>) {
     commands.spawn((
         Text::new("GAME OVER"),
         TextFont {
@@ -33,6 +35,25 @@ pub fn setup_game_over_ui(mut commands: Commands) {
         },
         GameOverUI,
     ));
+    commands.spawn((
+        Text::new(format!(
+            "Best: {}  Your Score: {}",
+            high_score.value, score.value
+        )),
+        TextFont {
+            font_size: 32.0,
+            ..default()
+        },
+        TextColor(Color::WHITE),
+        Node {
+            position_type: PositionType::Absolute,
+            align_self: AlignSelf::Center,
+            justify_self: JustifySelf::Center,
+            top: Val::Percent(48.0),
+            ..default()
+        },
+        HighScoreText,
+    ));
     commands.spawn((
         Text::new("Press R to Restart"),
         TextFont {
@@ -53,7 +74,7 @@ pub fn setup_game_over_ui(mut commands: Commands) {
 
 pub fn cleanup_game_over_ui(
     mut commands: Commands,
-    query: Query<Entity, Or<(With<GameOverUI>, With<RestartMessage>)>>,
+    query: Query<Entity, Or<(With<GameOverUI>, With<RestartMessage>, With<HighScoreText>)>>,
 ) {
     for entity in &query {
         commands.entity(entity).despawn();
@@ -73,7 +94,7 @@ pub fn cleanup_game_entities(
 
 // --- Start Menu UI ---
 
-pub fn setup_start_menu_ui(mut commands: Commands) {
+pub fn setup_start_menu_ui(mut commands: Commands, high_score: Res<HighScore>) {
     commands
         .spawn((
             Node {
@@ -99,6 +120,19 @@ pub fn setup_start_menu_ui(mut commands: Commands) {
                     ..default()
                 },
             ));
+            parent.spawn((
+                Text::new(format!("Best: {}", high_score.value)),
+                TextFont {
+                    font_size: 32.0,
+                    ..default()
+                },
+                TextColor(Color::WHITE),
+                Node {
+                    margin: UiRect::bottom(Val::Px(30.0)),
+                    ..default()
+                },
+                HighScoreText,
+            ));
             parent
                 .spawn((
                     Button,
@@ -127,7 +161,10 @@ pub fn setup_start_menu_ui(mut commands: Commands) {
         });
 }
 
-pub fn cleanup_start_menu_ui(mut commands: Commands, query: Query<Entity, With<StartMenuUI>>) {
+pub fn cleanup_start_menu_ui(
+    mut commands: Commands,
+    query: Query<Entity, Or<(With<StartMenuUI>, With<HighScoreText>)>>,
+) {
     for entity in &query {
         commands.entity(entity).despawn();
     }

src/lib.rs

@@ -8,6 +8,7 @@ pub mod components;
 pub mod constants;
 pub mod enemy;
 pub mod game_state;
+pub mod persistence;
 pub mod player;
 pub mod resources;
 pub mod stage;
@@ -15,8 +16,7 @@ pub mod starfield;
 pub mod systems;
 
 use bullet::{
-    check_bullet_collisions, check_enemy_bullet_player_collisions, move_bullets,
+    check_bullet_collisions, check_enemy_bullet_player_collisions, move_bullets, move_enemy_bullets,
-    move_enemy_bullets,
 };
 use components::TractorBeam;
 use constants::{PLAYER_RESPAWN_DELAY, STARTING_LIVES, WINDOW_HEIGHT, WINDOW_WIDTH};
@@ -34,14 +34,14 @@ use player::{
     player_shoot, respawn_player,
 };
 use resources::{
-    AttackDiveTimer, CurrentStage, EnemySpawnTimer, FormationState, PlayerLives,
+    AttackDiveTimer, CurrentStage, EnemySpawnTimer, FormationState, HighScore, PlayerLives,
     PlayerRespawnTimer, RestartPressed, Score, StageConfigurations,
 };
 use stage::check_stage_clear;
 use starfield::scroll_starfield;
 use systems::{
-    animate_explosion, player_exists, player_vulnerable, setup, should_respawn_player,
+    animate_explosion, check_high_score, player_exists, player_vulnerable, setup,
-    update_window_title,
+    should_respawn_player, update_window_title,
 };
 
 pub fn run() {
@@ -73,6 +73,9 @@ pub fn run() {
             timer: Timer::new(Duration::from_secs_f32(3.0), TimerMode::Once),
         })
         .init_resource::<Score>()
+        .insert_resource(HighScore {
+            value: persistence::load(&persistence::save_path()).value,
+        })
         .init_resource::<CurrentStage>()
         .init_resource::<FormationState>()
         .init_resource::<StageConfigurations>()
@@ -121,7 +124,10 @@ pub fn run() {
             start_menu_button_system.run_if(in_state(AppState::StartMenu)),
         )
         // Game over.
-        .add_systems(OnEnter(AppState::GameOver), setup_game_over_ui)
+        .add_systems(
+            OnEnter(AppState::GameOver),
+            (setup_game_over_ui, check_high_score),
+        )
         .add_systems(OnExit(AppState::GameOver), cleanup_game_over_ui)
         .add_systems(
             Update,

src/systems.rs

@@ -2,9 +2,12 @@ use bevy::prelude::*;
 use std::time::Duration;
 
 use crate::components::{Explosion, Invincible, Player};
-use crate::constants::{EXPLOSION_BASE_SIZE, EXPLOSION_COLOR, EXPLOSION_DURATION, EXPLOSION_MAX_SIZE};
+use crate::constants::{
+    EXPLOSION_BASE_SIZE, EXPLOSION_COLOR, EXPLOSION_DURATION, EXPLOSION_MAX_SIZE,
+};
+use crate::persistence;
 use crate::player::spawn_player_ship;
-use crate::resources::{CurrentStage, PlayerLives, Score, is_special_stage};
+use crate::resources::{is_special_stage, CurrentStage, HighScore, PlayerLives, Score};
 use crate::starfield::spawn_starfield;
 
 pub fn setup(mut commands: Commands) {
@@ -27,6 +30,17 @@ pub fn should_respawn_player(lives: Res<PlayerLives>, query: Query<&Player>) ->
     query.is_empty() && lives.count > 0
 }
 
+// --- High Score ---
+
+pub fn check_high_score(score: Res<Score>, mut high_score: ResMut<HighScore>) {
+    if score.value > high_score.value {
+        high_score.value = score.value;
+        if let Err(e) = persistence::save(&high_score, &persistence::save_path()) {
+            eprintln!("Failed to save high score: {e}");
+        }
+    }
+}
+
 // --- HUD ---
 
 pub fn update_window_title(