style(web): 移除顶栏 AI 快捷操作区并优化差旅领导意见事件样式

- TopBar 移除 AI 模式下的公司切换/AI 模式切换快捷操作块及 showAiModeUtilityActions 计算属性，清理 top-bar.css 对应样式
- TravelRequestDetailView 领导意见事件重构为状态/意见/审批人结构化布局，travel-request-detail-view.css 补充对应样式
- 同步更新 topbar-ai-mode-switch、ai-sidebar-rail-mode、travel-request-detail-leader-approval 测试

web/src/assets/styles/components/top-bar.css

@@ -380,14 +380,6 @@
   min-width: 0;
 }
 
-.topbar-utility-actions {
-  display: inline-flex;
-  align-items: center;
-  justify-content: flex-end;
-  gap: 10px;
-  min-width: 0;
-}
-
 .topbar-icon-btn {
   position: relative;
   width: 34px;
@@ -1329,10 +1321,6 @@
     gap: 12px;
   }
 
-  .topbar-utility-actions {
-    gap: 8px;
-  }
-
   .topbar-icon-btn {
     width: 30px;
     height: 30px;
@@ -1413,7 +1401,6 @@
   .search-wrap,
   .search-wrap.wide,
   .topbar-toolset,
-  .topbar-utility-actions,
   .detail-alert-strip,
   .month-chip,
   .qa-filter,
@@ -1429,10 +1416,6 @@
     justify-content: flex-end;
   }
 
-  .topbar-utility-actions {
-    justify-content: flex-end;
-  }
-
   .topbar-ai-mode-toggle {
     width: 34px;
     height: 34px;