docs(editor): improve editor-app build documentation and add build:rapier2d script

- Add `pnpm build:rapier2d` command to automate Rapier2D WASM build process
- Fix gen-src.mjs path to correctly locate thirdparty/rapier.js
- Update init.ts to work with new wasm-pack web target (auto-initialization)
- Fix behavior-tree-editor build config for asset-system dependency
- Update README_CN.md and README.md with simplified build instructions

packages/editor/plugins/behavior-tree-editor/tsup.config.ts

@@ -2,8 +2,7 @@ import { defineConfig } from 'tsup';
 import { editorOnlyPreset } from '../../../tools/build-config/src/presets/plugin-tsup';
 
 export default defineConfig({
-    ...editorOnlyPreset({
-        external: ['@esengine/asset-system']
-    }),
-    tsconfig: 'tsconfig.build.json'
+    ...editorOnlyPreset({}),
+    tsconfig: 'tsconfig.build.json',
+    noExternal: ['@esengine/asset-system']
 });