fix: 修复页面间状态丢失问题并优化选择页面

- 修复选择审批人后再选择抄送人导致状态丢失的问题
- 使用独立的 sessionStorage key (selectedApprovers, selectedCc)
- 组件每次挂载时从 sessionStorage 恢复状态
- 只在提交/保存成功后清除 sessionStorage
- 优化人员选择页面布局和样式
- 更新 CLAUDE.md 文档记录问题和解决方案

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

frontend/src/pages/business-trip/select-cc.module.css

@@ -1,25 +1,42 @@
 .page {
-  min-height: 100vh;
+  height: 100vh;
+  max-height: 100vh;
+  max-width: 100vw;
+  width: 100%;
   background: #f5f5f5;
   display: flex;
   flex-direction: column;
+  overflow: hidden;
 }
 
 .navBar {
   background: #fff;
   border-bottom: 1px solid #f0f0f0;
+  flex-shrink: 0;
+  width: 100%;
+  z-index: 10;
 }
 
 .searchSection {
   background: #fff;
   padding: 8px 16px;
   border-bottom: 1px solid #f0f0f0;
+  flex-shrink: 0;
+  width: 100%;
+  z-index: 8;
 }
 
 .userList {
   flex: 1;
   overflow-y: auto;
+  overflow-x: hidden;
   padding: 8px 0;
+  padding-bottom: 70px;
+  display: flex;
+  flex-direction: column;
+  width: 100%;
+  max-width: 100%;
+  -webkit-overflow-scrolling: touch;
 }
 
 .userItem {
@@ -31,17 +48,26 @@
   border-bottom: 1px solid #f5f5f5;
   cursor: pointer;
   transition: background 0.2s;
+  flex-shrink: 0;
+  width: 100%;
+  max-width: 100%;
+  box-sizing: border-box;
 }
 
 .userItem:active {
   background: #f5f5f5;
 }
 
+.userItem.selected {
+  background: #e6f7ff;
+}
+
 .userInfo {
   display: flex;
   align-items: center;
   gap: 12px;
   flex: 1;
+  min-width: 0;
 }
 
 .avatar {
@@ -49,32 +75,77 @@
   height: 44px;
   border-radius: 50%;
   background: #f0f0f0;
+  flex-shrink: 0;
 }
 
 .userDetails {
   display: flex;
   flex-direction: column;
   gap: 4px;
+  flex: 1;
+  min-width: 0;
+  overflow: hidden;
 }
 
 .name {
   font-size: 15px;
   color: #333;
   font-weight: 500;
+  white-space: nowrap;
+  overflow: hidden;
+  text-overflow: ellipsis;
+}
+
+.email {
+  font-size: 13px;
+  color: #999;
+  white-space: nowrap;
+  overflow: hidden;
+  text-overflow: ellipsis;
 }
 
 .position {
   font-size: 13px;
   color: #999;
+  white-space: nowrap;
+  overflow: hidden;
+  text-overflow: ellipsis;
+}
+
+.checkIcon {
+  color: #1677ff;
+  font-size: 20px;
+  flex-shrink: 0;
 }
 
 .checkbox {
   --size: 20px;
   --icon-size: 14px;
+  flex-shrink: 0;
+}
+
+.loadMore {
+  padding: 16px;
+  text-align: center;
+  color: #1677ff;
+  font-size: 14px;
+  cursor: pointer;
+  flex-shrink: 0;
+}
+
+.loadMore:active {
+  opacity: 0.7;
 }
 
 .footer {
+  position: fixed;
+  bottom: 0;
+  left: 0;
+  right: 0;
   background: #fff;
   padding: 12px 16px;
+  padding-bottom: max(12px, env(safe-area-inset-bottom));
   border-top: 1px solid #f0f0f0;
+  z-index: 999;
+  box-shadow: 0 -2px 8px rgba(0, 0, 0, 0.1);
 }