Keep the tip deck to two-column layouts and fix its buttons' ripple

The deck was hidden only on a handheld, so between 600 and 925px — where the
chat list is a drawer over the only column — it still sat behind the drawer.
It now isn't mounted at all in a single-column layout
(`isLessThanFloatingLeftSidebar`): nothing is drawn or fetched until the window
is wide enough for two columns, and narrowing it tears the deck down again.

Clicking a card's segmented button killed its ripple: every card rebuilds its
button array when the selection moves, and `For` keyed the fresh objects by
reference and recreated every button. `Index` keeps them by position and only
updates them. A selected button's ripple is also primary now, like the active
tab of a horizontal menu, instead of always secondary.

The cards take their corner radius from `--main-column-border-radius`, the same
as the app's columns.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>