Hostinger Horizons quick wins and improvements

This release includes six improvements to the Horizons experience: the "Migrate Website" button is now hidden on the Horizons page in hPanel, with "Add website" redirecting straight to Horizons; clicking "Connect domain" for Horizons sites now shows domains relevant to that specific project; your prompt input is now preserved when you reload the page; the AI credit usage modal now displays your current website first, followed by others in alphabetical order; beta labels have been removed from integrated backend references; and saving package.json changes in the code editor now properly refreshes the preview and displays errors as expected.