test: verify saveBase64 content instead of on-disk size

With encryption enabled, saveBase64 goes through the regular save path and
the stored file is larger than the payload on Android, so asserting on
getFileSize failed. Read the file back with readAsDataURL instead.

Author: MxKevinBeqo

example/__tests__/file-system.harness.ts

@@ -313,8 +313,11 @@ describe('NativeFileSystem', () => {
       const base64 = btoa(String.fromCharCode(1, 2, 3, 4));
       await NativeFileSystem.saveBase64(base64, filePath);
 
-      const size = await NativeFileSystem.getFileSize(filePath);
-      expect(size).toBe(4);
+      // Not asserting on getFileSize: saveBase64 goes through the regular save
+      // path, so with encryption enabled the on-disk size includes overhead.
+      // readAsDataURL decrypts, so it verifies the stored content.
+      const dataUrl = await NativeFileSystem.readAsDataURL(filePath);
+      expect(dataUrl).contains(base64);
 
       await NativeFileSystem.remove(filePath);
     });