refactor: 升级vite至v6版本，升级sass至最新版，重构主题写法，弃用@pureadmin/theme (#1188)

* refactor: 升级`vite`至`v6`版本，升级`sass`至最新版，重构主题写法，删除`@pureadmin/theme`

src/views/account-settings/index.vue

@@ -131,7 +131,7 @@ getMine().then(res => {
 
 <style lang="scss">
 .pure-account-settings {
-  background: $menuBg;
+  background: var(--pure-theme-menu-bg);
 }
 
 .pure-account-settings-menu {
@@ -140,12 +140,12 @@ getMine().then(res => {
 
   .el-menu-item {
     height: 48px !important;
-    color: $menuText;
+    color: var(--pure-theme-menu-text);
     background-color: transparent !important;
     transition: color 0.2s;
 
     &:hover {
-      color: $menuTitleHover !important;
+      color: var(--pure-theme-menu-title-hover) !important;
     }
 
     &.is-active {