refactor: 重构后端目录结构和命名规范

- 将后端目录名从大写改为小写 (Controller->controller 等)
- 将命名空间从 App\ 改为 app\ (符合 webman 官方规范)
- 移除不必要的 bootstrap 目录
- 完善出差审批业务功能：
  - 添加删除草稿功能
  - 添加审批操作功能（同意/拒绝）
  - 完善审批详情页，显示审批人和审批记录
- 前端优化：
  - 调整列表页行高
  - 隐藏底部导航栏
  - 仪表盘只显示3个快捷入口

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

frontend/src/pages/business-trip/detail.module.css

@@ -60,6 +60,37 @@
   flex: 1;
 }
 
+.userList {
+  display: flex;
+  margin-bottom: 12px;
+}
+
+.userList:last-child {
+  margin-bottom: 0;
+}
+
+.userListLabel {
+  color: #999;
+  font-size: 14px;
+  width: 80px;
+  flex-shrink: 0;
+}
+
+.users {
+  display: flex;
+  flex-wrap: wrap;
+  gap: 8px;
+  flex: 1;
+}
+
+.user {
+  background: #f5f5f5;
+  padding: 4px 12px;
+  border-radius: 16px;
+  font-size: 13px;
+  color: #333;
+}
+
 .section {
   margin-bottom: 16px;
 }
@@ -94,11 +125,77 @@
 }
 
 .timeline {
-  padding: 16px 0;
+  padding: 8px 0;
 }
 
 .timelineItem {
   position: relative;
+  padding-left: 40px;
+  padding-bottom: 20px;
+}
+
+.timelineItem:last-child {
+  padding-bottom: 0;
+}
+
+.timelineItem:not(:last-child)::before {
+  content: '';
+  position: absolute;
+  left: 11px;
+  top: 24px;
+  bottom: 0;
+  width: 2px;
+  background: #e8e8e8;
+}
+
+.timelineDot {
+  position: absolute;
+  left: 0;
+  top: 0;
+  width: 24px;
+  height: 24px;
+  border-radius: 50%;
+  background: #1677ff;
+  display: flex;
+  align-items: center;
+  justify-content: center;
+}
+
+.timelineDotIcon {
+  font-size: 12px;
+}
+
+.timelineContent {
+  padding: 4px 0;
+}
+
+.timelineTitle {
+  font-weight: 500;
+  color: #333;
+  margin-bottom: 4px;
+  display: flex;
+  align-items: center;
+  gap: 8px;
+}
+
+.timelineName {
+  font-size: 13px;
+  color: #666;
+  font-weight: 400;
+}
+
+.timelineTime {
+  font-size: 12px;
+  color: #999;
+}
+
+.timelineComment {
+  font-size: 13px;
+  color: #666;
+  margin-top: 4px;
+  background: #f5f5f5;
+  padding: 6px 10px;
+  border-radius: 4px;
 }
 
 .timelineTitle {
@@ -152,6 +249,20 @@
   flex: 1;
 }
 
+.deleteBtn {
+  flex: 0 0 auto;
+  min-width: 120px;
+}
+
+.commentBox {
+  padding: 8px 0;
+}
+
+.commentBox :global(.adm-text-area) {
+  background: #f5f5f5;
+  border-radius: 8px;
+}
+
 :global(.adm-card-body) {
   padding: 16px;
 }