refactor: remove unused imports from multiple files

- Removed `std::time::Duration` import from `components.rs`, `resources.rs`, and `enemy.rs` as it was unnecessary.
- Cleaned up imports in `systems.rs` by removing `FormationState`.

src/components.rs

@@ -1,5 +1,4 @@
 use bevy::prelude::*;
-use std::time::Duration; // Needed for Timer in Player
 
 // --- Components ---
 #[derive(Component)]

src/enemy.rs

@@ -2,16 +2,13 @@ use bevy::prelude::*;
 use std::time::Duration;
 
 use crate::components::{Enemy, EnemyBullet, EnemyState, EnemyType, FormationTarget};
-use crate::constants::{ // Added WINDOW_WIDTH
-    ENEMY_BULLET_PLAYER_COLLISION_THRESHOLD, ENEMY_BULLET_SIZE, ENEMY_BULLET_SPEED,
-    ENEMY_SHOOT_INTERVAL, ENEMY_SIZE, ENEMY_SPEED, FORMATION_BASE_Y, FORMATION_COLS,
-    FORMATION_ENEMY_COUNT, FORMATION_X_SPACING, FORMATION_Y_SPACING, WINDOW_HEIGHT, WINDOW_WIDTH,
+use crate::constants::{ // Only keeping used constants
+    ENEMY_BULLET_SIZE, ENEMY_SIZE, ENEMY_SPEED, WINDOW_HEIGHT, WINDOW_WIDTH,
 };
 use crate::resources::{
-    AttackDiveTimer, CurrentStage, EnemySpawnTimer, FormationState, PlayerLives,
-    PlayerRespawnTimer, StageConfigurations, // Make sure StageConfigurations is imported if not already
+    AttackDiveTimer, CurrentStage, EnemySpawnTimer, FormationState,
+    StageConfigurations,
 };
-use crate::game_state::AppState;
 
 pub fn spawn_enemies(
     mut commands: Commands,
@@ -278,8 +275,6 @@ pub fn trigger_attack_dives(
 
     // Only proceed if the timer finished AND the formation is complete
     if timer.timer.just_finished() && formation_state.formation_complete {
-        // Find all enemies currently in formation
-        let mut available_enemies: Vec<Entity> = Vec::new();
         // Get the current stage config
         let config_index = (stage.number as usize - 1) % stage_configs.stages.len();
         let current_config = &stage_configs.stages[config_index];

src/resources.rs

@@ -1,5 +1,4 @@
 use bevy::prelude::*;
-use std::time::Duration; // Needed for Timer
 
 // --- Resources ---
 #[derive(Resource)]

src/systems.rs

@@ -1,7 +1,7 @@
 use bevy::prelude::*;
 
 use crate::components::{Invincible, Player};
-use crate::resources::{CurrentStage, FormationState, PlayerLives, Score};
+use crate::resources::{CurrentStage, PlayerLives, Score};
 use crate::player::spawn_player_ship; // Import the helper function
 
 // --- Setup ---