fix(ui): align the Erudit blank star with neighbouring tiles

Rack: the empty-blank star is now top-anchored level with the letters and a
touch larger (was centred, sitting low). Board and Stats best-move tiles: the
placed-blank star's ink is centred on the value digits' line (was slightly
high). CSS-only nudges; pixel offsets measured against the rendered glyphs.

ui/src/components/WordTiles.svelte

@@ -56,8 +56,10 @@
     font-size: 7px;
     font-weight: 600;
   }
-  /* A placed Erudit blank ("звёздочка") shows its star where the (absent) point value sits. */
+  /* A placed Erudit blank ("звёздочка") shows its star where the (absent) point value sits,
+     its ink kept on the value digits' line (mirrors the board tile). */
   .blankmark {
-    font-size: 10px;
+    font-size: 8px;
+    bottom: 0;
   }
 </style>