style(chat): remove icone do header para mais espaco

Remove o icone circular preto do header do chat
quando esta dentro de uma conversa, mantendo mais
espaco para informacoes do ticket.

🤖 Generated with [Claude Code](https://claude.com/claude-code)

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

src/components/chat/chat-widget.tsx

@@ -726,13 +726,10 @@ export function ChatWidget() {
                       <ChevronLeft className="size-5" />
                     </button>
                   )}
-                  <div className="flex size-10 items-center justify-center rounded-full bg-black text-white">
-                    <MessageCircle className="size-5" />
-                  </div>
                   <div>
                     <div className="flex items-center gap-2">
                       <p className="text-sm font-semibold text-slate-900">
-                        {activeSession ? `#${activeSession.ticketRef}` : "Chat"}
+                        #{activeSession?.ticketRef ?? chatData?.ticketId?.slice(-4)}
                       </p>
                       {/* Indicador online/offline */}
                       {liveChat?.hasMachine && (