feat: implement ECS architecture with game entity management

- Introduced a new Entity-Component-System (ECS) architecture for the game.
- Created foundational components such as Transform, Velocity, Health, and Collidable.
- Developed systems for handling input, movement, collision detection, and rendering.
- Added game logic for player control, coin collection, and obstacle interactions.
- Implemented a performance monitor for real-time metrics display.
- Enhanced game initialization and entity creation processes.

This update significantly refactors the game structure, improving maintainability and scalability.

src/systems/RenderSystem.js

@@ -0,0 +1,28 @@
+import { System } from '../ecs/System.js';
+import { Transform } from '../components/Transform.js';
+import { MeshComponent } from '../components/MeshComponent.js';
+
+/**
+ * RenderSystem - syncs Three.js mesh positions with Transform components
+ */
+export class RenderSystem extends System {
+  constructor(scene) {
+    super();
+    this.scene = scene;
+  }
+
+  update(_deltaTime) {
+    const entities = this.getEntities(Transform, MeshComponent);
+
+    for (const entityId of entities) {
+      const transform = this.getComponent(entityId, Transform);
+      const meshComp = this.getComponent(entityId, MeshComponent);
+
+      // Sync mesh transform with component
+      meshComp.mesh.position.copy(transform.position);
+      meshComp.mesh.rotation.copy(transform.rotation);
+      meshComp.mesh.scale.copy(transform.scale);
+    }
+  }
+}
+