feat(03-07): InstallPrompt — iOS walkthrough banner + Android beforeinstallprompt
- Implement isIOSSafariNonStandalone(): iOS UA + navigator.standalone detection
- Implement useAndroidInstallPrompt(): captures beforeinstallprompt, exposes canInstall/triggerInstall
- InstallPrompt renders nothing when display-mode:standalone or navigator.standalone (already installed)
- iOS branch: dismissible banner with 'Install FamilySync' heading, 'How to install' link
opens 5-step walkthrough sheet (exact UI-SPEC copy, orange #F5A623 step number annotation)
- Android branch: banner with 'Install' button shown only when canInstall=true
- localStorage.installPromptDismissed persists banner dismissal
- role="banner", dismiss aria-label="Dismiss install prompt", 44px touch targets
- Mount <InstallPrompt /> in CalendarShell (phone: below AppNav; desktop: top of content area)
- InstallPrompt.test.tsx GREEN (5 behavior tests); full PWA suite 44 tests green; tsc clean
Lucas Berger
e0fb34b252