重构项目结构：整理gitignore，移动source目录到根目录，统一依赖管理

src/ECS/index.ts

@@ -0,0 +1,11 @@
+export { Entity } from './Entity';
+export { Component } from './Component';
+export { CoreEvents, ECSEventType, EventPriority, EVENT_TYPES, EventTypeValidator } from './CoreEvents';
+export * from './Systems';
+export * from './Utils';
+export { Scene } from './Scene';
+export { EntityManager, EntityQueryBuilder } from './Core/EntityManager';
+export * from './Core/Events';
+export * from './Core/Query';
+export * from './Core/Performance';
+export * from './Core/Storage';