fix(website): use desktop package version in JSON-LD softwareVersion

[Augustas11]

Summary

• The Docusaurus head-tag JSON-LD block hardcoded softwareVersion: '0.1.49' while the desktop workspace currently ships 0.1.86 (per apps/desktop/package.json).
• Google Rich Results, app-store-style snippets, and any LLM scraping the site for structured data therefore report a 37-version-stale value.
• The fix imports apps/desktop/package.json directly and references desktopPkg.version so the literal stays in sync with each desktop release.
• The matching downloadUrl already points at …/releases/latest, so the actual download was unaffected — only the structured-data field was drifting.

Reproduction

$ grep softwareVersion apps/website/docusaurus.config.ts   # was 0.1.49
$ grep '"version"' apps/desktop/package.json               # 0.1.86

Testing

• pnpm install + a website build was not run in this clean worktree; native dependencies in the wider monorepo make a from-scratch install heavy.
• The change is 2 lines (one new import, one literal → reference rewrite). The pnpm workspace builds desktop before website per topological order, so the import resolves at config load time.
• Visual / structured-data verification recommended on a maintainer worktree: apps/website build should succeed (strict broken-link policy still passes) and the rendered JSON-LD should match apps/desktop/package.json:version.