feat: 完善审批退回流程与报销申请关联

后端优化报销单访问策略和常量定义，增强退回原因和审批状态
流转，前端完善退回对话框和审批交互组件，新增报销申请关联
模型，优化文档中心行数据和审批收件箱工具函数，增强引导
流程和会话模型，补充单元测试覆盖。

web/src/components/travel/TravelRequestApprovalDialog.vue

@@ -27,11 +27,27 @@
         <span>{{ summaryLabel }}</span>
         <strong>{{ nextStage }}</strong>
       </div>
-      <div class="submit-confirm-row">
-        <span>{{ opinionTitle }}</span>
-        <strong>{{ normalizedOpinion }}</strong>
-      </div>
     </div>
+
+    <label class="approval-opinion-field">
+      <span>
+        {{ opinionTitle }}
+        <em v-if="opinionRequired">必填</em>
+      </span>
+      <textarea
+        :value="currentOpinion"
+        maxlength="500"
+        :required="opinionRequired"
+        :disabled="busy"
+        :placeholder="opinionPlaceholder"
+        :aria-label="opinionTitle"
+        @input="handleOpinionInput"
+      ></textarea>
+      <small>
+        <span>{{ opinionHint }}</span>
+        <strong>{{ currentOpinion.length }}/500</strong>
+      </small>
+    </label>
   </ConfirmDialog>
 </template>
 
@@ -53,10 +69,83 @@ const props = defineProps({
   summaryLabel: { type: String, required: true },
   nextStage: { type: String, required: true },
   opinionTitle: { type: String, required: true },
-  opinion: { type: String, default: '' }
+  opinion: { type: String, default: '' },
+  opinionPlaceholder: { type: String, default: '' },
+  opinionHint: { type: String, default: '' },
+  opinionRequired: { type: Boolean, default: false }
 })
 
-const emit = defineEmits(['close', 'confirm'])
+const emit = defineEmits(['close', 'confirm', 'update:opinion'])
 
-const normalizedOpinion = computed(() => props.opinion.trim() || '未填写')
+const currentOpinion = computed(() => String(props.opinion || ''))
+
+function handleOpinionInput(event) {
+  emit('update:opinion', event.target.value)
+}
 </script>
+
+<style scoped>
+.approval-opinion-field {
+  display: grid;
+  gap: 8px;
+  margin-top: 14px;
+}
+
+.approval-opinion-field > span {
+  display: inline-flex;
+  align-items: center;
+  gap: 8px;
+  color: #334155;
+  font-size: 12px;
+  font-weight: 850;
+}
+
+.approval-opinion-field em {
+  border-radius: 999px;
+  padding: 2px 7px;
+  background: rgba(var(--theme-primary-rgb), .1);
+  color: var(--theme-primary-active);
+  font-style: normal;
+  font-size: 11px;
+  font-weight: 850;
+}
+
+.approval-opinion-field textarea {
+  width: 100%;
+  min-height: 96px;
+  resize: vertical;
+  padding: 12px;
+  border: 1px solid #d7e0ea;
+  border-radius: 8px;
+  background: #fff;
+  color: #0f172a;
+  font-size: 13px;
+  line-height: 1.6;
+  outline: none;
+}
+
+.approval-opinion-field textarea:focus {
+  border-color: rgba(var(--theme-primary-rgb), .5);
+  box-shadow: 0 0 0 3px var(--theme-focus-ring);
+}
+
+.approval-opinion-field small {
+  display: flex;
+  align-items: center;
+  justify-content: space-between;
+  gap: 12px;
+  color: #64748b;
+  font-size: 12px;
+  line-height: 1.5;
+}
+
+.approval-opinion-field small span {
+  min-width: 0;
+}
+
+.approval-opinion-field small strong {
+  flex: 0 0 auto;
+  color: var(--theme-primary-active);
+  font-weight: 850;
+}
+</style>

web/src/components/travel/TravelRequestReturnDialog.vue

@@ -4,6 +4,7 @@
     :title="title"
     :description="description"
     :busy="busy"
+    :application="application"
     @close="emit('close')"
     @confirm="emit('confirm', $event)"
   />
@@ -16,7 +17,8 @@ defineProps({
   open: { type: Boolean, required: true },
   title: { type: String, required: true },
   description: { type: String, required: true },
-  busy: { type: Boolean, required: true }
+  busy: { type: Boolean, required: true },
+  application: { type: Boolean, default: false }
 })
 
 const emit = defineEmits(['close', 'confirm'])