Welcome pop-up, first three sign-ins

A modal over the post-login home, shown on sign-ins one, two and three. The anatomy is the library's .o-welcome; this file adds only the scrim hang. Every string is filler: copy is Maher's, Arabic is Orbitra's (Ahmed facilitates). The visibility rule needs a server-held sign-in count, with the documented seven-day fallback. The in-page welcome card on the home covers the same job and both cannot ship for the same visits: which form ships is an open Shane call, logged in the spec.