style(admin): enhance collapsible summary hover/focus and arrow

public/css/admin-components.css

@@ -662,6 +662,42 @@
 
 .collapsible-summary{
     user-select:none;
+    position:relative;
+    padding-right:32px; /* 预留箭头空间 */
+    border-radius:var(--adm-radius-sm, 10px);
+    transition:background .15s ease, box-shadow .15s ease, color .15s ease;
+    outline:none;
+}
+
+/* Ant Design Pro-ish：summary hover/active/focus 交互 */
+.collapsible-summary:hover{
+    background:var(--adm-surface-tint);
+}
+
+.collapsible-summary:focus{
+    box-shadow:0 0 0 3px var(--adm-primary-focus-ring), var(--adm-shadow-sm);
+}
+
+/* 右侧箭头（替代原生 marker） */
+.collapsible-summary::after{
+    content:"";
+    position:absolute;
+    right:14px;
+    top:50%;
+    width:8px;
+    height:8px;
+    border-right:2px solid var(--adm-text-muted, #94a3b8);
+    border-bottom:2px solid var(--adm-text-muted, #94a3b8);
+    transform:translateY(-50%) rotate(45deg);
+    transition:transform .15s ease, border-color .15s ease;
+}
+
+.collapsible-summary:hover::after{
+    border-color:var(--adm-text-secondary, #64748b);
+}
+
+.collapsible[open] > .collapsible-summary::after{
+    transform:translateY(-50%) rotate(225deg);
 }
 
 .collapsible-body{