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

scripts/db/display_metadata_validator.py

@@ -219,6 +219,8 @@ def validate_options_json(options_json: str | None) -> tuple[list[str], list[str
                 errors.append(f"options_json.{key} 必须是安全标识符，当前为 {raw!r}")
         if parsed.get("filter_column") not in (None, "") and "filter_value" not in parsed:
             warnings.append("options_json lookup 声明了 filter_column 但未提供 filter_value")
+        if "multiple" in parsed and not isinstance(parsed.get("multiple"), bool):
+            errors.append("options_json lookup.multiple 必须是布尔值")
         return errors, warnings
 
     if not isinstance(parsed, list):