feat(ui): Erudit blank tiles carry the star (✻) mark

The Erudit variant's blank is the "звёздочка", so render it with a star.
An empty rack blank (and its drag ghost) shows ✻ centred; a placed blank
keeps its designated letter and carries ✻ where the (absent) point value
sits — on the board and in the Stats best-move tiles. The Scrabble variants
are unchanged. Gated by usesStarBlank() in lib/variants.ts.

ui/src/components/WordTiles.svelte

@@ -1,12 +1,14 @@
 <script lang="ts">
   // A best-move word drawn as a row of game tiles, mirroring the board's placed-tile
   // look (letter top-left, point value bottom-right) at a small fixed size. A blank tile
-  // shows its letter but no value, exactly as on the board. Letters are upper-cased for
-  // display. The tile values ride on each tile, so this renders without the variant's
-  // alphabet table (which the statistics screen has not cached).
-  import type { BestMoveTile } from '../lib/model';
+  // shows its letter but no value, exactly as on the board; in Erudit it also carries the
+  // blank's star (✻) in the value corner. Letters are upper-cased for display. The tile
+  // values ride on each tile, so this needs only the variant id (for the star) — not the
+  // variant's alphabet table, which the statistics screen has not cached.
+  import type { BestMoveTile, Variant } from '../lib/model';
+  import { usesStarBlank, BLANK_STAR } from '../lib/variants';
 
-  let { word }: { word: BestMoveTile[] } = $props();
+  let { word, variant }: { word: BestMoveTile[]; variant: Variant } = $props();
 
   const label = $derived(word.map((t) => t.letter).join('').toUpperCase());
 </script>
@@ -15,7 +17,11 @@
   {#each word as tile, i (i)}
     <span class="tile" class:blank={tile.blank} aria-hidden="true">
       <span class="letter">{tile.letter.toUpperCase()}</span>
-      {#if !tile.blank}<span class="val">{tile.value}</span>{/if}
+      {#if !tile.blank}
+        <span class="val">{tile.value}</span>
+      {:else if usesStarBlank(variant)}
+        <span class="val blankmark">{BLANK_STAR}</span>
+      {/if}
     </span>
   {/each}
 </span>
@@ -50,4 +56,8 @@
     font-size: 7px;
     font-weight: 600;
   }
+  /* A placed Erudit blank ("звёздочка") shows its star where the (absent) point value sits. */
+  .blankmark {
+    font-size: 10px;
+  }
 </style>