1.0.0

feat: add responsive layout and enhance custom scaffold features (#2)

* feat: add responsive layout and enhance custom scaffold features

Introduce a new `ResponsiveLayout` widget to support mobile, tablet, and desktop layouts. Enhance `CustomScaffoldPlus` with new features including background gradients, overlay images, height factor control, and customizable animations. Update documentation and example app to demonstrate new capabilities.

* refactor: improve code readability and update package version

Refactor code to improve readability by reducing unnecessary line breaks and aligning nested widgets. Update the package version in pubspec.lock to 1.0.0 to reflect the latest release.