fix: 登录浮层面板高度降为 85vh（更紧凑）

cfc-frontend/components/login-sheet.vue

@@ -257,8 +257,8 @@ export default {
   left: 0;
   right: 0;
   bottom: 0;
-  height: 92vh;
-  max-height: 92vh;
+  height: 85vh;
+  max-height: 85vh;
   background: linear-gradient(180deg, #fffaf3 0%, #fff3e4 100%);
   border-radius: 32rpx 32rpx 0 0;
   overflow: hidden;