Implemented lazy loading

src/myfasthtml/core/constants.py

@@ -1,14 +1,16 @@
 from enum import Enum
 
-DEFAULT_COLUMN_WIDTH = 100
+NO_DEFAULT_VALUE = object()
 
 ROUTE_ROOT = "/myfasthtml"
 
 # Datagrid
 ROW_INDEX_ID = "__row_index__"
+DATAGRID_DEFAULT_COLUMN_WIDTH = 100
 DATAGRID_PAGE_SIZE = 1000
 FILTER_INPUT_CID = "__filter_input__"
 
+
 class Routes:
   Commands = "/commands"
   Bindings = "/bindings"