feat: dedup expected data by handover_no before export submit

- store.get_existing_handover_nos: query PG expected_record.handover_no

- inject dedup skip before submitting export in zto/yunda/anneng/shunxin

- shunxin reads RTS handover_no from waybill-list view (method 1)

- force-redownload switch threaded via task_spec -> dispatch -> impl

- schema: add idx_expected_handover index

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

inbound_verify/sites/baishi.py

@@ -137,7 +137,7 @@ def _close_tab(page, tab_name):
         print(f"   ⚠️ 关闭标签页【{tab_name}】时出错: {e}")
 
 
-def baishi_download_undelivered_data(page):
+def baishi_download_undelivered_data(page, force=False):
     """百世：一键提取应到未到（当日未扫）数据（内部含异常兜底重试，路由层无感）。"""
 
     return with_retry(