The document vault and the admin area each carried a formatBytes; the
same backup read 1.25 MB in one and 1.2 MB in the other, and only the
vault knew gigabytes. The vault rule (one decimal below 100, up to GB,
digits in the reader's locale) now lives in src/lib/format/bytes.ts and
takes the locale, so the server-rendered share page uses it too. A test
holds the definition to that one module.