feat: 完善差旅票据行程提取与费用明细回填逻辑

增强文档智能识别的票据场景关键词和字段提取能力，优化
会话关联草稿报销单的解析路径，修复费用明细合并和票据
去重边界问题，前端改进报销创建和审批详情交互，补充单
元测试覆盖。

server/tests/test_document_intelligence.py

@@ -72,6 +72,24 @@ def test_document_intelligence_prefers_train_ticket_for_railway_e_ticket_invoice
     assert any(field.label == "金额" and field.value == "354元" for field in insight.fields)
 
 
+def test_document_intelligence_labels_train_ticket_date_as_train_departure_time() -> None:
+    insight = build_document_insight(
+        filename="铁路电子客票.pdf",
+        summary="铁路电子客票",
+        text=(
+            "中国铁路电子客票 开票日期 2026-02-18 "
+            "G456 上海虹桥-武汉 2026-02-20 08:30开 票价:￥354.00"
+        ),
+    )
+
+    assert insight.document_type == "train_ticket"
+    assert any(
+        field.key == "date" and field.label == "列车出发时间" and field.value == "2026-02-20 08:30"
+        for field in insight.fields
+    )
+    assert not any(field.label == "开票日期" for field in insight.fields)
+
+
 def test_document_intelligence_service_keeps_rule_fields_without_model_correction() -> None:
     engine = create_engine(
         "sqlite+pysqlite:///:memory:",