fix: 供销协议折扣明细通过product_supplier_mapping关联产品

产品与供应商的关联在product_supplier_mapping表（supplier_org_id/external_supplier_id），
不在product.org_id。修复后：
1. 查合同→供应商→supplier_orgid+supplier_id
2. 查product_supplier_mapping获取该供应商的产品ID列表
3. 用产品ID列表过滤product表

supplychain/init.py

@@ -995,36 +995,51 @@ async def get_agreement_discount_items(request):
 async def get_contract_discount_items(request):
     """Return products with discount status for a supply contract.
     
-    Products are filtered by the contract's supplier org_id — only products
-    belonging to the supplier should appear in the supplier agreement.
+    Products are linked to suppliers via product_supplier_mapping, not org_id.
     """
     params_kw = getattr(request._run_ns, 'params_kw', {}) or {}
     contract_id = params_kw.get('contract_id') or params_kw.get('id')
     if not contract_id:
         return []
     env = request._run_ns
-    # Get supplier_orgid from the contract's supplier
-    supplier_orgid = '0'
+    # Get supplier info from contract
+    supplier_orgid = None
+    supplier_id = None
     async with get_sor_context(env, 'supplychain') as sor:
         rows = await sor.sqlExe(
-            "SELECT s.orgid FROM suppliers s "
+            "SELECT s.orgid, s.id as supplier_id FROM suppliers s "
             "JOIN supply_contracts sc ON sc.supplier_id = s.id "
             "WHERE sc.id = ${cid}$",
             {'cid': contract_id}
         )
-        if rows and rows[0].orgid:
+        if rows:
             supplier_orgid = rows[0].orgid
-    # Get products from sage — only this supplier's products
+            supplier_id = rows[0].supplier_id
+    if not supplier_orgid:
+        return []
+    # Get product IDs mapped to this supplier via product_supplier_mapping
+    product_ids = set()
+    async with get_sor_context(env, 'supplychain') as sor:
+        mappings = await sor.sqlExe(
+            "SELECT product_id FROM product_supplier_mapping "
+            "WHERE status = '1' AND (supplier_org_id = ${oid}$ OR external_supplier_id = ${sid}$)",
+            {'oid': supplier_orgid, 'sid': supplier_id}
+        )
+        for m in mappings:
+            product_ids.add(m.product_id)
+    if not product_ids:
+        return []
+    # Get products from sage
     products = []
     async with get_sor_context(env, 'sage') as sor:
         rows = await sor.sqlExe(
-            """SELECT p.id as productid, p.product_name, p.product_code, p.price as sale_price,
-                      pc.id as category_id, pc.name as category_name
-               FROM product p
-               LEFT JOIN product_category pc ON p.category_id = pc.id
-               WHERE p.status = '1' AND p.org_id = ${oid}$
-               ORDER BY pc.sort_order, pc.name, p.sort_order, p.product_name""",
-            {'oid': supplier_orgid}
+            "SELECT p.id as productid, p.product_name, p.product_code, p.price as sale_price, "
+            "pc.id as category_id, pc.name as category_name "
+            "FROM product p "
+            "LEFT JOIN product_category pc ON p.category_id = pc.id "
+            "WHERE p.status = '1' AND p.id IN (" + ",".join(repr(pid) for pid in product_ids) + ") "
+            "ORDER BY pc.sort_order, pc.name, p.sort_order, p.product_name",
+            {}
         )
         for r in rows:
             products.append({