iOS Safari has no beforeinstallprompt API, so the portal's Install
button (?install=1) silently did nothing there. IosInstallHint now
shows Share -> Add to Home Screen steps on Safari, or a prompt to
switch to Safari first if opened in another iOS browser/in-app
webview (those can't install PWAs on iOS at all).
Also added apple-mobile-web-app-title + apple-touch-icon so the
home screen icon isn't a page screenshot.
Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>
