Education & Reference Widget Pack

# Changelog

## 1.0.2
- Added required root package `slug` for current Core manifest validation.
- Added/normalized widget-level slugs for contained widgets.
- Revalidated flat ZIP root, JSON descriptors, PHP syntax, and archive integrity.

## 1.0.1
- Fixed Store/Core package detection by placing a recognized `widget.json` at the ZIP root.
- ZIP now has a flat package root instead of an extra enclosing directory.
- Added root `widget.php` compatibility registry for contained widgets.
- Added installer metadata listing every contained widget path.
- Added release QA for root-package detection.