fix(ui): pin the landscape confirm button into the freed tile slot

Follow-up to the contour review: with the rack now exactly seven fixed-size slots in the
narrow landscape panel, the 56px confirm button (sized for the roomy portrait rack) was
wider than the single slot a staged tile frees, so it overlapped the now-rightmost tile.
Match the button width to one landscape tile slot, so it sits inside the freed slot with
its right edge level with the rack's right edge — the mirror of the first tile's left edge.

ui/src/game/Game.svelte

@@ -1544,6 +1544,14 @@
   .make:disabled {
     opacity: 0.4;
   }
+  /* Landscape: the rack fills a narrow fixed-width panel with exactly seven tile slots, so the 56px
+     button (sized for the roomy portrait rack) is wider than the single slot a staged tile frees and
+     overlaps the now-rightmost tile. Match the button to one landscape tile slot (its width formula),
+     so it sits inside the freed slot with its right edge level with the rack's right edge — the
+     mirror of the first tile's left edge. */
+  .game-land .make {
+    width: calc((100% - 2 * var(--pad) - 6 * 5px) / 7);
+  }
   /* The move-history header: leave (active) / export (finished) on the left, comms on the
      right, icon-only. Sticky so it stays atop the scrolling move list. */
   .hhead {