Restore sign-in after PWA logout

Reopening the installed Miracle app after signing out now shows a working sign-in screen. This fixes the blank window reported in Brave on desktop.

Private account content stays hidden and cannot receive clicks while account access is being checked or after sign-out. No saved tasks or notes are removed by this fix.

Added browser checks for logout, cached app reopening, small windows, and failed account requests to help prevent this issue from returning.