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/core/package.json

@@ -36,6 +36,7 @@
     "typecheck": "tsc --noEmit"
   },
   "dependencies": {
+    "@homarr/version": "workspace:^0.1.0",
     "@t3-oss/env-nextjs": "catalog:",
     "better-sqlite3": "catalog:",
     "dns-caching": "catalog:",