The loader keeps no migrations any more: an asset of the old type autotile (before #131) is an unknown type and dropped, and a tilemap layer with the cell map of the first version (before #134) loads empty; every project is saved in the current format, and the two tests now pin that the old shapes are not read (#137)

Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>

src/core/store/tilemapCells.ts

@@ -113,8 +113,3 @@ export function decodeCells(raw: {
   });
   return cells;
 }
-
-/** Whether a stored layer is in this format rather than the map of the first version (#128). */
-export function isStoredCells(raw: Record<string, unknown>): boolean {
-  return Array.isArray(raw.rows);
-}