Fixed two chat header display bugs

Two display bugs in the chat's floating header are fixed, across the hosted assistant page, the embedded web tag, and the dashboard playground.

The header menu no longer drifts to the center. On a site with no logo configured, the "more actions" menu button (and, on the embedded widget, the close button next to it) used to render centered in the header instead of staying in the top-right corner. Both now stay right-aligned whether or not a logo is set.

A just-sent message no longer hides behind the header. After sending a message, it could land scrolled up underneath the floating header instead of fully visible below it. The conversation now always scrolls to keep a new message clear of the header.

No action needed on your side: both fixes apply automatically.