docs: add lookup.multiple multi-select contract (v1.0.93)

tests/test_docs_standards.py

@@ -353,6 +353,8 @@ class TestDocsStandards(unittest.TestCase):
             "表与表之间：禁止 SQLite 外键",
             "禁止 SQLite 外键",
             "跨表引用 lookup",
+            "\"multiple\": true",
+            "Lookup 多选",
         ):
             self.assertIn(marker, text, msg=f"SCHEMA.md missing {marker!r}")
 
@@ -364,6 +366,7 @@ class TestDocsStandards(unittest.TestCase):
             "跨表引用：Lookup",
             "display_type: \"lookup\"",
             "extra_column",
+            "multiple",
             "数据管理新增/编辑",
             "_jiangchang_columns.description",
             "datetime_unix_seconds",