feat: Implement background shader and visual effects

- Added a new WGSL shader for background rendering with volumetric fog effects.
- Created components for game entities including Circle, Velocity, Explosion, and ChainReaction.
- Introduced game state management with GameState enum and LevelState resource.
- Implemented event system for explosion requests and circle destruction notifications.
- Developed plugins for game logic, input handling, movement, reactions, scoring, and UI.
- Configured game settings through GameConfig resource with adjustable parameters.
- Enhanced UI with configuration options and game over screens.
- Integrated spatial grid for efficient collision detection and explosion handling.

src/components.rs

@@ -0,0 +1,127 @@
+use bevy::{platform::collections::HashMap, prelude::*};
+
+#[derive(Component)]
+pub struct Circle {
+    pub radius: f32,
+}
+
+#[derive(Component)]
+pub struct Velocity(pub Vec2);
+
+#[derive(Component)]
+pub struct Explosion {
+    pub timer: Timer,
+    pub radius: f32,
+}
+
+#[derive(Component)]
+pub struct ChainReaction {
+    pub delay: Timer,
+    pub next_radius: f32,
+}
+
+#[derive(Resource)]
+pub struct Score {
+    pub total: u32,
+    pub multiplier: u32,
+    pub combo_timer: Timer,
+}
+
+#[derive(States, Default, Clone, PartialEq, Eq, Hash, Debug)]
+pub enum GameState {
+    #[default]
+    Menu,
+    Playing,
+    GameOver,
+}
+
+#[derive(Resource, Default)]
+pub struct SpatialGrid {
+    pub cells: HashMap<IVec2, Vec<Entity>>,
+    pub cell_size: f32,
+}
+
+impl SpatialGrid {
+    pub fn pos_to_cell(&self, pos: Vec2) -> IVec2 {
+        IVec2::new(
+            (pos.x / self.cell_size).floor() as i32,
+            (pos.y / self.cell_size).floor() as i32,
+        )
+    }
+
+    pub fn clear(&mut self) {
+        self.cells.clear();
+    }
+}
+
+#[derive(Component)]
+pub struct MainCamera;
+
+#[derive(Resource, Clone, Reflect)]
+#[reflect(Resource)]
+pub struct GameConfig {
+    pub circle_count_min: u32,
+    pub circle_count_max: u32,
+    pub circle_radius_min: f32,
+    pub circle_radius_max: f32,
+    pub max_velocity: f32,
+
+    pub explosion_radius: f32,
+    pub explosion_duration: f32,
+    pub chain_reaction_delay: f32,
+    pub secondary_explosion_factor: f32,
+
+    pub base_score: u32,
+    pub combo_window: f32,
+
+    pub cell_size: f32,
+    pub manual_explosion_limit: u32,
+}
+
+impl Default for GameConfig {
+    fn default() -> Self {
+        Self {
+            circle_count_min: 1000,
+            circle_count_max: 5000,
+            circle_radius_min: 10.0,
+            circle_radius_max: 50.0,
+            max_velocity: 1000.0,
+            explosion_radius: 100.0,
+            explosion_duration: 0.5,
+            chain_reaction_delay: 0.1,
+            secondary_explosion_factor: 0.5,
+            base_score: 10,
+            combo_window: 0.5,
+            cell_size: 100.0,
+            manual_explosion_limit: 1,
+        }
+    }
+}
+
+#[derive(Clone, Copy, Debug, PartialEq, Eq, Default)]
+pub enum LevelStatus {
+    #[default]
+    Playing,
+    Victory,
+    Defeat(usize),
+}
+
+#[derive(Resource)]
+pub struct LevelState {
+    pub explosions_left: u32,
+    pub settle_timer: Timer,
+    pub status: LevelStatus,
+}
+
+impl Default for LevelState {
+    fn default() -> Self {
+        Self {
+            explosions_left: 1,
+            settle_timer: Timer::from_seconds(1.25, TimerMode::Once),
+            status: LevelStatus::Playing,
+        }
+    }
+}
+
+#[derive(Component)]
+pub struct GameEntity;