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:",

packages/request-handler/src/update-checker.ts

@@ -6,8 +6,7 @@ import { fetchWithTrustedCertificatesAsync } from "@homarr/core/infrastructure/h
 import { createLogger } from "@homarr/core/infrastructure/logs";
 import { ErrorWithMetadata } from "@homarr/core/infrastructure/logs/error";
 import { createGetSetChannel, createLockChannel } from "@homarr/redis";
-
-import packageJson from "../../../package.json";
+import { VERSION } from "@homarr/version";
 
 const logger = createLogger({ module: "updateCheckerRequestHandler" });
 
@@ -22,7 +21,7 @@ type UpdateCheckCacheEntry = {
   checkedAt: number | null;
 };
 
-const updateCheckCacheVersion = `v2:${packageJson.version}`;
+const updateCheckCacheVersion = `v2:${VERSION}`;
 const freshUpdateCheckChannel = createGetSetChannel<UpdateCheckCacheEntry>(
   `update-checker:fresh:${updateCheckCacheVersion}`,
 );
@@ -69,7 +68,7 @@ const getCachedAvailableUpdatesAsync = async (): Promise<UpdateCheckCacheEntry>
 
   try {
     const attemptedAt = Date.now();
-    const availableUpdates = await getAvailableUpdatesAsync(packageJson.version);
+    const availableUpdates = await getAvailableUpdatesAsync(VERSION);
     const result: UpdateCheckCacheEntry = {
       availableUpdates,
       attemptedAt,