Deprecated @import in Bootstrap SCSS causes issues in modern environments (e.g. Next.js)

Bootstrap is still using @import in its .scss files, which is deprecated in Dart Sass and causes issues in modern build systems like Next.js (especially with strict or future Sass modes).

Steps to Reproduce:

• Use Bootstrap via Sass in a Next.js project.
• Build the project with strict Sass (or latest versions).

Expected:

• Bootstrap should use @use and @forward for modular and future-proof compatibility.

Actual:

• Sass throws deprecation warnings or errors depending on config.

Suggested Fix:

• Migrate internal Bootstrap SCSS to the modern @use system, as recommended by Sass maintainers

Environment:

• Next.js 14+
• Dart Sass
• Bootstrap version: 5.x.x

[julien-deramond]

Closing as duplicate of some issues we have already that will be tackled by #41112 and/or #41236