Stage 17 round 5 — board interaction & UI polish

- Even zoom: interpolate the board scroll toward a pre-clamped target as the real width
  grows/shrinks, so it magnifies A->B in one motion instead of lurching and snapping back
  near the edges/centre. Recentre only on a zoom toggle, never on a focus change — so a
  2nd+ placed tile and a hovered dragged tile no longer jump the board.
- Drag: highlight the aimed-at empty cell as a drop target; hover-hold auto-zoom now
  fires only for the first (zoom-in) hold.
- Pinch zoom: two-finger spread/close toggles zoom toward the pinch midpoint (preventDefault
  only for two touches, so one-finger scroll stays native); a second finger aborts a drag.
- Shuffle hop capped at 0.3s and disabled under reduce-motion.
- Make-move is a borderless icon button, disabled while the pending word is known illegal.
- Variant display names: english & russian_scrabble -> Scrabble/Скрэббл, erudit ->
  Erudite/Эрудит; the in-game title shows the variant name (was always 'Scrabble').

ui/src/lib/variants.ts

@@ -11,13 +11,22 @@ export interface VariantOption {
   label: MessageKey;
 }
 
-// ALL_VARIANTS lists every variant in display order.
+// ALL_VARIANTS lists every variant in display order. The labels are display names, not
+// language names: both Scrabble variants render as "Scrabble"/"Скрэббл" and Erudit as
+// "Erudite"/"Эрудит" (Stage 17) — the offered list is language-gated, so within one
+// language the names stay distinct.
 export const ALL_VARIANTS: VariantOption[] = [
   { id: 'english', label: 'new.english' },
   { id: 'russian_scrabble', label: 'new.russian' },
   { id: 'erudit', label: 'new.erudit' },
 ];
 
+// variantNameKey returns the i18n key for a variant's display name (used by the in-game
+// title and the lobby cards).
+export function variantNameKey(v: Variant): MessageKey {
+  return ALL_VARIANTS.find((o) => o.id === v)?.label ?? 'new.english';
+}
+
 // VARIANT_LANGUAGE maps each variant to its game language. en -> English;
 // ru -> Russian + Эрудит.
 export const VARIANT_LANGUAGE: Record<Variant, 'en' | 'ru'> = { english: 'en', russian_scrabble: 'ru', erudit: 'ru' };