Add 👇 emoji button to toolbar

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

public/index.html

@@ -107,6 +107,7 @@ button.gen:hover{background:#094fa3;}
       <button onclick="ins('📣')">📣</button>
       <button onclick="ins('🔑')">🔑</button>
       <button onclick="ins('👆 ')">👆</button>
+      <button onclick="ins('👇 ')">👇</button>
       <button onclick="ins('☑️ ')">☑️</button>
       <button onclick="ins('🌍')">🌍</button>
       <button onclick="ins('⏰')">⏰</button>