Show the teacher refresh button as an icon only

src/pages/Chat/TeacherCompanion.tsx

@@ -58,7 +58,6 @@ export function TeacherCompanion({ companion, open, onOpen, onToggle, bubbleRef,
         title={refreshMessage || '刷新智能体'} disabled={loading || companion.refreshing} aria-busy={companion.refreshing}
         onMouseDown={(event) => event.preventDefault()} onClick={() => { setIntroductionId(null); void companion.refresh(); }}>
         <RefreshCw className={`h-3.5 w-3.5 shrink-0 ${companion.refreshing ? 'animate-spin motion-reduce:animate-none' : ''}`} aria-hidden="true" />
-        <span>{companion.refreshing ? '刷新中' : companion.refreshStatus === 'error' ? '刷新失败' : companion.refreshStatus === 'success' ? '已更新' : '刷新'}</span>
       </button>
       <span className="sr-only" role="status" aria-live="polite">{refreshMessage}</span>
       {!invitation && welcomes.length > 0 && <div ref={bubbleRef} className="teacher-welcome-presence" data-testid="teacher-welcomes" aria-label="认识这里的老师">