style: 优化个人中心和偏好设置弹窗样式，重构工作入口为精致分屏布局并移除首字徽标

frontend/src/styles/main.css

@@ -3,8 +3,6 @@
  * 参考 shadcn-admin 的轻量、中性、分层风格
  */
 
-@import url("https://fonts.googleapis.com/css2?family=Manrope:wght@400;500;600;700;800&display=swap");
-
 :root {
   /* 品牌色 - 低饱和蓝灰 */
   --ctms-primary: #3f5d75;
@@ -1057,6 +1055,17 @@ body.is-desktop-runtime .el-dialog {
   max-width: min(calc(100vw - 72px), var(--el-dialog-width, 960px));
 }
 
+/* profile-settings-dialog / desktop-preferences-dialog：移除外层卡片外壳，内容区自带圆角阴影 */
+body.is-desktop-runtime .profile-settings-dialog,
+body.is-desktop-runtime .desktop-preferences-dialog {
+  overflow: visible !important;
+  border: none !important;
+  border-radius: 0 !important;
+  background: transparent !important;
+  box-shadow: none !important;
+  backdrop-filter: none !important;
+}
+
 body.is-desktop-runtime .el-message-box {
   width: min(420px, calc(100vw - 72px));
   padding: 0;
@@ -1099,12 +1108,14 @@ body.is-desktop-runtime .el-dialog__body {
 }
 
 body.is-desktop-runtime .desktop-preferences-dialog {
-  background: #f2f4f7;
+  background: transparent !important;
+  box-shadow: none !important;
+  border-radius: 0 !important;
 }
 
 body.is-desktop-runtime .desktop-preferences-dialog .el-dialog__body {
   padding: 0;
-  background: #f2f4f7;
+  background: transparent !important;
 }
 
 body.is-desktop-runtime .el-dialog__footer,
@@ -1182,7 +1193,7 @@ body.is-desktop-runtime .msgbox-fade-leave-to .el-message-box {
 
 :root[data-ctms-theme="dark"] body.is-desktop-runtime .desktop-preferences-dialog,
 :root[data-ctms-theme="dark"] body.is-desktop-runtime .desktop-preferences-dialog .el-dialog__body {
-  background: #0f1721;
+  background: transparent !important;
 }
 
 :root[data-ctms-theme="dark"] body.is-desktop-runtime .el-dialog__header,