feat(db_compare): add PostgreSQL-based comparison engine with SF handling

Replace Excel-based undelivered comparison with DB queries for all four
sites. The engine anchors on actual scan_time, reverse-lookups handover
batches, and compares expected vs actual waybill-by-waybill.

Shunxin SF waybills: use COUNT(*) instead of COUNT(DISTINCT piece_no)
since SF piece numbers are random and not derivable from the waybill.

Changes:
- db_compare.py: new module with compare_site_date(), compare_site_batch(),
  write_result_excel(), and POST /compare API endpoint
- runtime.py: switch _site_undelivered_handler from compare.write_site_file
  (Excel) to db_compare (DB); downloads succeed independently of comparison
- server.py: add POST /compare endpoint with date validation
- docs: implementation plan for Shunxin DB comparison

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

inbound_verify/runtime.py

@@ -476,23 +476,44 @@ def _web_handler(site, download_func):
 
 
 def _site_undelivered_handler(site):
-    """4 站未到：下应到+实到 → 比对写 downloads/<站>-未到数据.xlsx。
-    任一下载失败 → 清掉旧未到文件、返回 False（前端不展示陈旧未到）。"""
+    """4 站未到：下应到+实到 → DB 比对 → 写 output/<站>-<日期>-未到数据.xlsx。
+    应到全量去重（已落库则跳过导出），因此比对不依赖 Excel 文件，走数据库查询。
+    下载成功则返回 True（比对失败不影响任务判定，数据已入库）。"""
 
     def handler(ctx, force=False, date=None):
-        # 各站下载入口约定返回 True/False；顺心历史返回 None（视为成功，与 dispatch 一致）
         exp_ok = TASK_HANDLERS[(site, "expected")](ctx, force, date) is not False
         act_ok = (
             (TASK_HANDLERS[(site, "actual")](ctx, force, date) is not False)
             if exp_ok
             else False
         )
-        if exp_ok and act_ok:
-            return compare.write_site_file(site)
-        stale = os.path.join(DOWNLOAD_DIR, SITE_UNDELIVERED_FILE.format(name=site))
-        if os.path.exists(stale):
-            os.remove(stale)
-        return False
+        if not exp_ok or not act_ok:
+            stale = os.path.join(DOWNLOAD_DIR, SITE_UNDELIVERED_FILE.format(name=site))
+            if os.path.exists(stale):
+                os.remove(stale)
+            return False
+
+        # ── DB 比对（替代旧 Excel 比对）──
+        try:
+            from inbound_verify import db_compare  # 懒导入，避免成环
+
+            if date:
+                target_date = date
+            else:
+                offset = state_store.get_offset(site, "expected")
+                target_date = (datetime.now().date() - timedelta(days=offset)).strftime(
+                    "%Y-%m-%d"
+                )
+
+            result = db_compare.compare_site_date(site, target_date)
+            if result is not None:
+                db_compare.write_result_excel(result)
+            else:
+                print(f">> [未到] {site} {target_date}: 当天无实到数据，跳过比对")
+        except Exception as e:
+            print(f">> [未到] {site} DB 比对异常（不影响下载结果）: {e}")
+
+        return True  # 下载成功即返回 True，比对失败不影响任务判定
 
     return handler