修复摸大红移动端分类栏主题色与固定滚动

选中态改为主题橙，左侧分类固定仅右侧商品列表滚动。

frontend/src/features/mohong/views/MobileMohongListView.vue

@@ -270,15 +270,18 @@ async function handleSupportClick() {
 
 <style scoped>
 .mohong-shell {
-  min-height: 100vh;
+  /* 固定视口高度：仅右侧列表滚动，左侧分类栏不随页面滚走 */
+  height: 100dvh;
+  max-height: 100dvh;
+  overflow: hidden;
   background: #f5f7fb;
-  padding-bottom: calc(64px + env(safe-area-inset-bottom));
+  padding-bottom: calc(52px + env(safe-area-inset-bottom));
   display: flex;
   flex-direction: column;
+  box-sizing: border-box;
 }
 .page-header {
-  position: sticky;
-  top: 0;
+  flex-shrink: 0;
   z-index: 10;
   display: flex;
   align-items: center;
@@ -325,11 +328,17 @@ async function handleSupportClick() {
   display: grid;
   grid-template-columns: 88px minmax(0, 1fr);
   min-height: 0;
+  overflow: hidden;
 }
 .cat-sidebar {
+  height: 100%;
+  min-height: 0;
   background: #f7f8fa;
+  overflow-x: hidden;
   overflow-y: auto;
+  -webkit-overflow-scrolling: touch;
   padding: 8px 0 16px;
+  overscroll-behavior: contain;
 }
 .cat-item {
   display: block;
@@ -345,15 +354,19 @@ async function handleSupportClick() {
 }
 .cat-item.active {
   background: #fff;
-  border-left-color: #ff4d4f;
-  color: #ff4d4f;
+  border-left-color: #ff6a00;
+  color: #ff6a00;
   font-weight: 700;
 }
 .list-panel {
-  background: #fff;
-  overflow-y: auto;
-  padding: 0 0 12px;
+  height: 100%;
   min-height: 0;
+  background: #fff;
+  overflow-x: hidden;
+  overflow-y: auto;
+  -webkit-overflow-scrolling: touch;
+  padding: 0 0 12px;
+  overscroll-behavior: contain;
 }
 .state-loading {
   padding: 40px 0;