v0.2.1 of nib_motion

A declarative, physics-based animation framework for Flutter. Inspired by Framer Motion — springs, gestures, variants, presence, scroll, FLIP layout, and GPU shader effects with zero external dependencies. Changelog excerpt: - Added example app demonstrating core primitives. - Fixed curly_braces_in_flow_control_structureslint issues. - Improved pub.dev package description and metadata. - Added CI/CD via GitHub Actions.