style(frontend): 全站背景图 webp 化(bg.jpg 4MB→251KB 压缩 + bg.webp)＋品牌工具页默认策略调优（品牌检测默认改精确匹配 Simple、Terms 后置）＋任务面板/登录页/亚马逊控制台观感微调

frontend-vue/src/shared/components/tasks/HistoryTaskLayer.vue

@@ -123,7 +123,7 @@ async function confirmBatchDelete() {
   padding: 5px 12px;
   border: 1px solid #3e4a62;
   border-radius: 6px;
-  background: #222;
+  background: #242424;
   color: #c8d2e2;
   font-size: 12px;
   cursor: pointer;

frontend-vue/src/shared/components/tasks/TaskCenterPanel.vue

@@ -111,7 +111,7 @@ withDefaults(defineProps<{
 .result-list-wrap {
   border: 1px solid #2e3a52;
   border-radius: 8px;
-  background: #1c2333;
+  background: #242424;
   min-height: 180px;
 }
 

frontend-vue/src/shared/components/tasks/TaskItemCard.vue

@@ -43,7 +43,7 @@ defineProps<{
   border: 1px solid #2e3a52;
   border-radius: 8px;
   margin-bottom: 8px;
-  background: #222;
+  background: #242424;
 }
 
 .left {

frontend-vue/src/shared/components/tasks/TaskStatCards.vue

@@ -27,7 +27,7 @@ defineProps<{
   padding: 14px 16px;
   border: 1px solid #2e3a52;
   border-radius: 8px;
-  background: #1c2333;
+  background: #242424;
 }
 
 .summary-card strong {