Parameterize Shunxin query window and document it in example config

- site_shunxin: replace the hardcoded 1天 radio with config-driven
  shunxin.query_days, set the date range via the ant-picker, and add a
  two-pass query/retry to clear stale "暂无数据" DOM state; return True
  on completion
- config.example.yaml: add the shunxin section (query_days) so the
  example matches what the code reads

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

config.example.yaml

@@ -20,6 +20,13 @@ debug:
   # 留空或不匹配时将回退为全量模式。
   target_site: ""
 
+# ----------------------------------------------------------------------------
+# 顺心捷达 (https://sxne.sxjdfreight.com)
+# ----------------------------------------------------------------------------
+shunxin:
+  # 应到 / 实到数据的查询时间范围（单位：天，向前回溯 N 天至今天）。
+  query_days: 1
+
 # ----------------------------------------------------------------------------
 # 百世快运 (https://v5.800best.com)
 # ----------------------------------------------------------------------------