chore(ui): change hints symbol for backward unicode compatibility

ui/src/game/Game.svelte

@@ -1735,7 +1735,7 @@
          idle gate while it is closed; tapping then only explains when it opens (doHint), and the lock
          lifts live at the unlock moment. -->
     <button class="tab" disabled={busy || !isMyTurn || !netReady} onclick={doHint}>
-      <span class="sq" data-coach="game-hints">🛟{#if hintGated}<span class="lock" aria-hidden="true">🔒</span>{/if}</span>
+      <span class="sq" data-coach="game-hints">✨{#if hintGated}<span class="lock" aria-hidden="true">🔒</span>{/if}</span>
       <span class="lbl">{t('game.hint')}</span>
     </button>
   {:else}
@@ -1745,7 +1745,7 @@
       disabled={busy || !isMyTurn || !netReady || hintCount <= 0}
       onconfirm={doHint}
     >
-      <span class="sq" data-coach="game-hints">🛟{#if hintCount > 0}<span class="badge">{hintCount}</span>{/if}</span>
+      <span class="sq" data-coach="game-hints">✨{#if hintCount > 0}<span class="badge">{hintCount}</span>{/if}</span>
       <span class="lbl">{t('game.hint')}</span>
     </TapConfirm>
   {/if}