refactor(sass): rename files to start with an underscore (_) as requi…

…red for partials

Error:
- SCSS partials were not prefixed with an underscore (_), which is required for them to be recognized as partials by the Sass compiler.
Without the underscore, Sass treats these files as standalone stylesheets, attempting to compile them directly, which can lead to errors or unwanted output.

Solution:
- Rename all SCSS partials to start with an underscore (_) to ensure they are treated as partials, meaning they will only be included when explicitly imported into other files.