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/version/package.json

@@ -0,0 +1,20 @@
+{
+  "name": "@homarr/version",
+  "version": "0.1.0",
+  "private": true,
+  "license": "Apache-2.0",
+  "type": "module",
+  "exports": {
+    ".": "./index.ts"
+  },
+  "scripts": {
+    "clean": "rm -rf .turbo node_modules",
+    "format": "oxfmt .",
+    "lint": "oxlint",
+    "typecheck": "tsc --noEmit"
+  },
+  "devDependencies": {
+    "@homarr/tsconfig": "workspace:^0.1.0",
+    "typescript": "catalog:"
+  }
+}