refactor: drop redundant end-of-file barrel exports in download-assets + util/fs

Both files had `export { name1, name2 }` blocks at EOF re-exporting
already-file-private declarations. Since no other module consumes the
re-exports, they're no-ops. Drop them.

  - packages/cli/scripts/download-assets.mts: ASSETS, downloadAsset,
    downloadAssets are CLI-script entry-point helpers (script invoked
    via `node`, not imported)
  - packages/cli/scripts/util/fs.mts: findUpSync is a local helper

Author: jdalton

packages/cli/scripts/download-assets.mts

@@ -266,5 +266,3 @@ if (fileURLToPath(import.meta.url) === process.argv[1]) {
     process.exitCode = 1
   })
 }
-
-export { ASSETS, downloadAsset, downloadAssets }

packages/cli/scripts/util/fs.mts

@@ -46,5 +46,3 @@ function findUpSync(name, options) {
   }
   return undefined
 }
-
-export { findUpSync }