feat: 添加Font Awesome字体图标及相关样式文件

新增Font Awesome的字体文件、SVG图标及LESS/SCSS样式文件，包括基础样式、图标定义和响应式布局支持。添加了多种常用图标如播放、停止、加减乘除等，并支持列表布局和屏幕阅读器优化。

scss/_screen-reader.scss

@@ -0,0 +1,14 @@
+// screen-reader utilities
+// -------------------------
+
+// only display content to screen readers
+.sr-only,
+.#{$fa-css-prefix}-sr-only {
+  @include fa-sr-only;
+}
+
+// use in conjunction with .sr-only to only display content when it's focused
+.sr-only-focusable,
+.#{$fa-css-prefix}-sr-only-focusable {
+  @include fa-sr-only-focusable;
+}