refactor(server): user_agent/steward/ocr 等服务重构并适配关联任务

- user_agent 拆分 application/locations/knowledge/response/review 四个子模块，接入申请位置语义与关联草稿分支
- steward planner/runtime/slot/plan_builder 决策链路重构，travel_reimbursement_calculator/orchestrator_expense_query 适配
- ocr/document_preview/document_intelligence/receipt_folder 复用预览与资产缓存，expense_claim_draft_flow/application_handoff 适配
- pyproject.toml 新增依赖，paddleocr bootstrap 脚本与 server_start.sh 调整
- 更新差旅/交通/通信等财务规则表，同步 document_intelligence/ocr/receipt_folder/user_agent 等测试

server/tests/test_document_intelligence.py

@@ -84,6 +84,33 @@ 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_train_ticket_uses_railway_merchant_not_invoice_title() -> None:
+    insight = build_document_insight(
+        filename="2月20_武汉-上海.pdf",
+        summary="电子发票（铁路电子客票）；发票监；统一 制",
+        text=(
+            "电子发票（铁路电子客票）\n"
+            "发票号码:26429165800002785705 湖北\n"
+            "开票日期:2026年05月18日\n"
+            "武汉站 G458 上海虹桥站\n"
+            "Wuhan Shanghaihongqiao\n"
+            "2026年02月20日 07:55开 06车01B号 二等座\n"
+            "票价:￥354.00\n"
+            "4201061987****1615 曹笑竹\n"
+            "电子客票号:6580061086021391007342026\n"
+            "购买方名称:曹笑竹 统一社会信用代码:\n"
+            "买票请到12306 发货请到95306\n"
+            "中国铁路祝您旅途愉快"
+        ),
+    )
+
+    assert insight.document_type == "train_ticket"
+    fields = {field.label: field.value for field in insight.fields}
+    assert fields["商户"] == "中国铁路"
+    assert fields["金额"] == "354元"
+    assert fields["列车出发时间"] == "2026-02-20 07:55"
+
+
 def test_document_intelligence_recovers_train_ticket_from_english_station_ocr_text() -> None:
     insight = build_document_insight(
         filename="2月20_武汉-上海.pdf",