v1.2.0 - Standalone Desktop App, Preview Site and Zip Export

HATS now runs as a standalone desktop app, has a preview-only website and
exports themes as ready-to-install zip files.

Added

• Standalone desktop app for macOS, Windows and Linux. It runs the designer
  and the live preview on your own computer, with no Home Assistant needed.
• Preview-only website at https://homeriz.github.io/hats/. Open it with
  ?repo=OWNER/REPO to see any public GitHub theme repo exactly as its author
  published it, in the real Home Assistant frontend. It installs nothing.
• Download .zip in the export dialog: the theme and its background image in
  the folders Home Assistant expects, a per-view snippet and a README with the
  install steps.
• Select several themes in the library and export them in one zip.
• Import dialog for a theme YAML, a background image and a per-view snippet.
• UIX as a styling engine next to card-mod, chosen in the Doctor.

Changed

• In the library, a click selects a theme and a double click or the eye icon
  opens its preview. Export is shown only on the Designer tab.
• The standalone app hides what only makes sense inside Home Assistant, and
  Download replaces Install.
• The live preview is one Home page with an example of every card family.
• Each card switch now matches what the theme generates. Stack-in-Card
  merges its inner cards into one glass card, and the Button Card ripple is
  stronger on hover and press.

Fixed

• The live preview no longer goes blank after Edit in Designer.
• The per-view background snippet now works on themes made in HATS.
• The selected sidebar item stays visible when card-mod is off.
• The local server refuses unexpected Host headers, and the desktop window
  only follows links that point to the app.

Desktop downloads

The builds are not code signed. On macOS, right-click the app and choose Open.
On Windows, choose More info, then Run anyway.