fix: Logo 点击区域修正 - z-index 提升到 100 + img pointer-events:none

核心修复:
- z-index: 20 → 100, 确保不被页面内容遮挡
- img 加 display:block 消除行内间隙
- img 加 pointer-events:none 让点击事件穿透到父级 a 标签
- a 标签加 cursor:pointer 显式指定

clientarea/hgcloud/css/regist.css

@@ -481,13 +481,14 @@
   position: fixed;
   top: 16px;
   left: 20px;
-  z-index: 20;
+  z-index: 100;
   display: flex;
   align-items: center;
   text-decoration: none;
   padding: 12px 14px;
   border-radius: 8px;
   transition: all 0.2s;
+  cursor: pointer;
 }
 
 .back-home-link:hover {
@@ -498,9 +499,6 @@
   height: 28px;
   width: auto;
   opacity: 1;
-  transition: opacity 0.2s;
-}
-
-.back-home-link:hover .back-home-logo {
-  opacity: 1;
+  display: block;
+  pointer-events: none;
 }