Prvw v0.4.0

Added

• Auto-updater: background update check, DMG download, .app bundle replacement. Restart to use the new version.
  PRVW_UPDATE_URL env var override for testing.
• Direct download buttons on website with architecture detection (Apple Silicon / Intel / Universal)
• PostHog session replay (cookieless, proxied through /ph/)
• Umami download tracking with arch, version, and source properties
• Sitemap via @astrojs/sitemap
• UptimeRobot monitoring for getprvw.com
• Terms and conditions and privacy policy pages
• Deploy infrastructure: webhook, CI auto-deploy on push to main

Fixed

• Download dropdown not opening (used DOMContentLoaded instead of astro:page-load)
• Updater: fix .app replacement (fs::rename over non-empty dir fails on macOS)