docs: migrate documentation from VitePress to Starlight (#361)

- Replace VitePress with Astro Starlight for documentation
- Reorganize document structure with better hierarchy
- Split large documents into sub-modules for better readability
- Add new sections: component, entity-query, serialization, system
- Support both Chinese (default) and English documentation
- Add responsive design and improved navigation

docs/.gitignore

@@ -0,0 +1,21 @@
+# build output
+dist/
+# generated types
+.astro/
+
+# dependencies
+node_modules/
+
+# logs
+npm-debug.log*
+yarn-debug.log*
+yarn-error.log*
+pnpm-debug.log*
+
+
+# environment variables
+.env
+.env.production
+
+# macOS-specific files
+.DS_Store