Replace fragile deep-relative 'package.json' imports across the monorepo
with a single source of truth: the new @homarr/version leaf package reads
the version once from the root package.json and exports it as VERSION.
Consumers now import by package name incl. the new User-Agent header in
fetchWithTrustedCertificatesAsync (packages/core):
- core, api (info router), analytics, request-handler (update checker)
This also removes all manually-maintained relative version imports.