perf: modular sass architecture (#2052)

- Modularized the Sass architecture to enhance code maintainability and reduce the output file size
- Replaced deprecated `@import` with `@use` / `@forward`

_sass/base/_reset.scss

@@ -0,0 +1,41 @@
+@use '../abstracts/mixins' as *;
+
+::-webkit-input-placeholder {
+  @include placeholder;
+}
+
+::-moz-placeholder {
+  @include placeholder;
+}
+
+:-ms-input-placeholder {
+  @include placeholder;
+}
+
+::-ms-input-placeholder {
+  @include placeholder;
+}
+
+::placeholder {
+  @include placeholder;
+}
+
+:focus::-webkit-input-placeholder {
+  @include placeholder-focus;
+}
+
+:focus::-moz-placeholder {
+  @include placeholder-focus;
+}
+
+:focus:-ms-input-placeholder {
+  @include placeholder-focus;
+}
+
+:focus::-ms-input-placeholder {
+  @include placeholder-focus;
+}
+
+:focus::placeholder {
+  @include placeholder-focus;
+}