refactor: replace @import with @use/@forward to remove Sass deprecation warnings

[mohamad4j]

Summary

This PR replaces all deprecated @import statements with the new @use and @forward syntax introduced in Dart Sass.
The change removes deprecation warnings during build and aligns the codebase with the current Sass best practices.

Changes

• Replaced @import statements with @use or @forward.
• Namespaced variables and mixins where necessary.
• Resolved duplicate variable conflicts (e.g., $trans-cubic-bezier) by making global mixins.
• Verified that all styles compile correctly without warnings.

Why

• @import is officially deprecated and will be removed in future Sass versions. Also there were many warning errors in build project
• @use/@forward provide better scoping, prevent global leaks, and improve maintainability.

Notes

• All tests and style builds pass successfully.
• No breaking changes for consumers of the package.

[guhweb]

@Maronato approve this pr plz?