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/views/TravelRequestDetailView.vue

@@ -165,15 +165,21 @@
                     :class="event.tone"
                   >
                     <div class="application-leader-opinion-event-head">
-                      <span>
+                      <span class="application-leader-opinion-event-status">
                         <i :class="event.type === 'returned' ? 'mdi mdi-arrow-u-left-top' : 'mdi mdi-check-circle-outline'"></i>
                         {{ event.title }}
                       </span>
                       <time v-if="event.time">{{ event.time }}</time>
                     </div>
-                    <p>{{ event.opinion }}</p>
-                    <footer>
-                      <span>{{ event.operator }}</span>
+                    <div class="application-leader-opinion-event-body">
+                      <span>意见</span>
+                      <p>{{ event.opinion }}</p>
+                    </div>
+                    <footer class="application-leader-opinion-event-foot">
+                      <span class="application-leader-opinion-operator">
+                        <em>审批人</em>
+                        {{ event.operator }}
+                      </span>
                       <span v-if="event.returnCount">第 {{ event.returnCount }} 次退回</span>
                     </footer>
                   </article>