desktop.html 0.1.0

Add Velopack installer, auto-update, and GitHub release workflow

- VelopackApp hook in Main handles install/update/uninstall (Start Menu
  shortcut creation and version migration).
- UpdateService checks GitHub releases; the app auto-downloads updates
  on startup and restarts cleanly to apply them. Dev builds are skipped.
- New CLI command: update check [--json].
- AppVersion now reads the assembly informational version so the release
  workflow can stamp it with -p:Version.
- .github/workflows/release.yml packs with vpk on v* tags and publishes
  installer + update artifacts; ci.yml builds and tests on push/PR.
- Docs: install section in README, Updates section in cli.md, and debug
  exe paths corrected to the win-x64 output folder.

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>