Initial Release #

• SmoothRectangleBorder — iOS-style continuous corner radius as a ShapeBorder. Works with Container, Card, Material, ElevatedButton, Dialog, and any widget that accepts ShapeBorder.
• SmoothRectangleClipper — CustomClipper<Path> for ClipPath to clip any widget to a squircle shape.
• smoothPath() — core path generation function using cubic bezier curves derived from Figma's smooth corners algorithm.
• Adjustable smoothing — 0.0 (standard circular) to 1.0 (maximum smoothness). Default 0.6 matches iOS/Figma.
• Symmetric corners — all 4 corners are identical regardless of widget aspect ratio.
• Zero dependencies — pure Dart/Flutter implementation.