refactor(version): centralize Homarr version in @homarr/version package

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.

packages/request-handler/package.json

@@ -29,6 +29,7 @@
     "@homarr/docker": "workspace:^0.1.0",
     "@homarr/integrations": "workspace:^0.1.0",
     "@homarr/redis": "workspace:^0.1.0",
+    "@homarr/version": "workspace:^0.1.0",
     "dayjs": "catalog:",
     "octokit": "catalog:",
     "superjson": "catalog:",