feat(pl): add customer stop pref service and unit tests

Co-authored-by: Cursor <cursoragent@cursor.com>

backend/tests/test_pl_customer_stop_pref_service.py

@@ -0,0 +1,54 @@
+"""客户装/送货默认记忆：条目合并规则"""
+from app.services.pl_customer_stop_pref_service import build_stop_pref_upsert_items
+
+
+def test_build_items_skips_empty_customer():
+    items = build_stop_pref_upsert_items(
+        load={"customer_id": "", "address": "A"},
+        deliveries=[{"customer_id": "c1", "address": "D1", "contact": "1", "notes": "n"}],
+    )
+    assert len(items) == 1
+    assert items[0]["stop_type"] == "delivery"
+    assert items[0]["customer_id"] == "c1"
+
+
+def test_build_items_load_and_delivery_independent():
+    items = build_stop_pref_upsert_items(
+        load={
+            "customer_id": "c1",
+            "customer_name": "甲",
+            "address": "装址",
+            "lng": 1.1,
+            "lat": 2.2,
+            "contact": "装联",
+            "notes": "装注",
+        },
+        deliveries=[
+            {
+                "customer_id": "c1",
+                "customer_name": "甲",
+                "address": "送址",
+                "contact": "送联",
+                "notes": "送注",
+            }
+        ],
+    )
+    assert len(items) == 2
+    by_type = {i["stop_type"]: i for i in items}
+    assert by_type["load"]["address"] == "装址"
+    assert by_type["delivery"]["address"] == "送址"
+
+
+def test_build_items_same_delivery_customer_last_wins():
+    items = build_stop_pref_upsert_items(
+        load=None,
+        deliveries=[
+            {"customer_id": "c1", "address": "第一段", "contact": "a", "notes": "1"},
+            {"customer_id": "c2", "address": "别家", "contact": "b", "notes": "2"},
+            {"customer_id": "c1", "address": "最后段", "contact": "c", "notes": "3"},
+        ],
+    )
+    delivery_c1 = [i for i in items if i["stop_type"] == "delivery" and i["customer_id"] == "c1"]
+    assert len(delivery_c1) == 1
+    assert delivery_c1[0]["address"] == "最后段"
+    assert delivery_c1[0]["contact"] == "c"