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/game/Rack.svelte

@@ -138,12 +138,14 @@
     font-size: 0.7rem;
     font-weight: 600;
   }
-  /* Erudit's blank ("звёздочка") shows its star centred on the otherwise empty tile face. */
+  /* Erudit's blank ("звёздочка") shows its star horizontally centred on the otherwise empty
+     tile face, top-aligned with the neighbouring letters (slightly larger so it reads). */
   .star {
     position: absolute;
-    inset: 0;
-    display: grid;
-    place-items: center;
-    font-size: 1.5rem;
+    top: 8%;
+    left: 0;
+    right: 0;
+    text-align: center;
+    font-size: 1.7rem;
   }
 </style>