fix: drop as const from PRETTIFY_OPTIONS to satisfy htmlfy types

`as const` typed `ignore` as a readonly tuple, which doesn't match
`UserConfig.ignore: string[]`, breaking CI typecheck.

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

Author: nperez0111

tests/src/unit/shared/formatConversion/export/exportTestExecutors.ts

@@ -13,7 +13,7 @@ import { ExportTestCase } from "./exportTestCase.js";
 
 // Preserve `<code>` whitespace so code-block snapshots show actual newlines
 // instead of having them collapsed by the prettifier.
-const PRETTIFY_OPTIONS = { tag_wrap: true, ignore: ["code"] } as const;
+const PRETTIFY_OPTIONS = { tag_wrap: true, ignore: ["code"] };
 
 export const testExportBlockNoteHTML = async <
   B extends BlockSchema,