fix(ui): landscape board zoom/pan + rack tile rendering, shorter mobile block label

Bugs surfaced while testing in VK but present on every platform (verified across
browsers, not VK-specific):

- Rack tiles: the letter used a fixed rem size, so in landscape — where tiles shrink
  below 46px in the narrow left panel — it overflowed and dropped into the bottom-left
  corner. Size it relative to the rack (cqw, like the board's labels; the tile's own
  container-query size resolves unreliably under flex + aspect-ratio).
- Landscape board zoom positioned "in two steps": the per-frame clamp-to-max reached
  the wide axis before the tall one. Interpolate both scroll axes together by time over
  the grow/shrink transition instead (settles on zoom-out too).
- The zoomed board could not be panned with a mouse (touch scrolls the overflow:auto
  viewport natively; a mouse cannot drag-scroll a div). Add a drag-to-pan handler, active
  only while zoomed, off pending tiles, past a small movement threshold, swallowing the
  trailing click so it does not also act on a cell.
- Shorten the in-game block-confirm label ru "Блокируем?" -> "В бан?" (the long form
  overflowed the seat score chip on mobile).

ui/src/lib/i18n/ru.ts

@@ -301,7 +301,7 @@ export const ru: Record<MessageKey, string> = {
   'game.exportGcg': 'Экспорт GCG',
   'game.gcgActiveOnly': 'Доступно после завершения игры.',
   'game.addFriendShort': 'В друзья?',
-  'game.blockShort': 'Блокируем?',
+  'game.blockShort': 'В бан?',
 
   'time.minutes': '{n} мин',
   'time.hours': '{n} ч',