feat: extract overlay scroll logic into reusable core module}
* Add new overlay-scroll.ts core module with shared scroll handling logic * Extract 256 lines of overlay scroll implementation for cross-framework use * Refactor Angular layout component to use new core module, reducing 49 lines * Refactor React Layout component to use new core module, reducing 39 lines * Refactor Vue Layout component to use new core module, reducing 60 lines * Update package.json version to reflect new functionality * Update README.md to document overlay scroll feature