Replicate the web app's glass-radio-group animation on the Flutter
contribute screen. Key changes:
- Sliding white glider pill behind active tab using AnimatedPositioned
- Bouncy spring physics: Cubic(0.37, 1.95, 0.66, 0.56) matching the
web CSS cubic-bezier that overshoots and settles
- Glassmorphic container: semi-transparent white bg with white border
- AnimatedDefaultTextStyle for smooth color transitions (blue active,
white 0.7 opacity inactive)
- AnimatedSize for icon appear/disappear on active tab
- LayoutBuilder for responsive tab width calculation
Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>
