solitaire: fly the cards home instead of blinking them there

A foundation only ever draws its top card, so the FLIP diff had nothing to
animate for the fifty-one cards buried underneath: an auto-finish was every
card vanishing at once, four kings stranded in the tableau row, and the
foundation flashes firing on empty slots.

Cards bound for a foundation now fly as ghosts, lifted out of the old DOM
into a fixed layer so the board underneath can re-render in one go while
they are still in the air. The card that lands is held invisible until its
ghost arrives, so the destination doesn't show the ending first.

The home counter was jumping straight to 52/52 over a board with fifty-one
cards still travelling. It walks up behind them now, on the same step ladder
as the ghosts, the flashes and the sound.

internal/web/static/css/input.css

@@ -1340,6 +1340,16 @@ html[data-phase="night"] {
   /* An empty place a card could be: the stock when it's spent, a foundation
      waiting for its ace, a column waiting for a king. Same footprint as a card,
      so nothing on the board reflows when one empties. */
+  /* Where cards go home. Solitaire lifts a copy of every card bound for a
+     foundation into here so it can keep flying while the board underneath it
+     redraws in one go. It never takes a click and it never scrolls. */
+  .pete-flight-layer {
+    position: fixed;
+    inset: 0;
+    z-index: 60;
+    pointer-events: none;
+  }
+
   .pete-slot {
     position: relative;
     display: grid;