fix(ecs): resolve ESM require is not defined error (#402)

- Add RuntimeConfig module as standalone runtime environment storage
- Core.runtimeEnvironment and Scene.runtimeEnvironment now read from RuntimeConfig
- Remove require() call in Scene.ts to fix Node.js ESM compatibility

Fixes ReferenceError: require is not defined when using scene.isServer in ESM environment

.changeset/fix-esm-require-bug.md

@@ -0,0 +1,11 @@
+---
+"@esengine/ecs-framework": patch
+---
+
+fix(ecs): 修复 ESM 环境下 require 不存在的问题
+
+- 新增 `RuntimeConfig` 模块，作为运行时环境配置的独立存储
+- `Core.runtimeEnvironment` 和 `Scene.runtimeEnvironment` 现在都从 `RuntimeConfig` 读取
+- 移除 `Scene.ts` 中的 `require()` 调用，解决 Node.js ESM 环境下的兼容性问题
+
+此修复解决了在 Node.js ESM 环境（如游戏服务端）中使用 `scene.isServer` 时报错 `ReferenceError: require is not defined` 的问题。