test: fix baseline store dirname resolution

tests/visual/baseline-store.ts

@@ -1,5 +1,9 @@
 import { readFileSync, writeFileSync } from "node:fs";
-import { resolve } from "node:path";
+import { fileURLToPath } from "node:url";
+import { dirname, resolve } from "node:path";
+
+const __filename = fileURLToPath(import.meta.url);
+const __dirname = dirname(__filename);
 
 export type KitchenSinkTheme = "default" | "light" | "contrast";