fix(docs): remove the ObjectOS One download surface from the docs site

apps/docs imported apps/objectos-one/package.json for the user-visible
version (lib/version.ts), breaking type-check after One's removal.
One is discontinued, so the whole download surface goes with it:

- app/[lang]/download page, components/download/*, lib/download-i18n.ts,
  lib/version.ts (no importers remain)
- nav: drop the Download item across all 7 locales (layout.shared.tsx)
- sitemap: drop the download entry

Verified locally: turbo type-check + build + test all green on the
docs-only workspace.

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_0162o68e5w3bpUBEVRQboUGG

Author: claude

apps/docs/app/[lang]/download/page.tsx

@@ -11,7 +11,6 @@ export default function sitemap(): MetadataRoute.Sitemap {
   // Top-level static pages (paths are locale-independent slugs).
   const staticPaths: Array<{ path: string; priority: number }> = [
     { path: '', priority: 1 },
-    { path: 'download', priority: 0.6 },
     { path: 'privacy', priority: 0.3 },
     { path: 'terms', priority: 0.3 },
   ];