fix(frontend): hover cards, balancer load, routing dnd, modal a11y, outbound crash

- ClientsPage/SettingsPage/XrayPage: add hoverable to bottom card/tabs so
  hover affordance matches the top card
- BalancerFormModal: lazy-init useState from props + destroyOnHidden so
  the form mounts with saved values instead of relying on a useEffect
  sync that could miss the first open
- RoutingTab: rewrite pointer drag — handlers are now defined inside the
  pointerdown closure so addEventListener/removeEventListener match;
  drag state lives on a ref (from/to/moved) so onUp reads the real
  indices, not stale closure values. Adds setPointerCapture so Windows
  and touch keep delivering events when the cursor leaves the handle.
- OutboundFormModal/InboundFormModal: blur the focused input before
  switching tabs to silence the aria-hidden-on-focused-element warning
- utils.isArrEmpty: return true for undefined/null arrays — the old form
  treated undefined as "not empty" which crashed VLESSSettings.fromJson
  when json.vnext was missing

frontend/src/pages/clients/ClientsPage.tsx

@@ -687,6 +687,7 @@ export default function ClientsPage() {
                   <Col span={24}>
                     <Card
                       size="small"
+                      hoverable
                       title={
                         <div className="card-toolbar">
                           <Button type="primary" size="small" icon={<PlusOutlined />} onClick={onAdd}>

frontend/src/pages/inbounds/InboundFormModal.tsx

@@ -701,6 +701,9 @@ export default function InboundFormModal({
   }, [t, refresh, parseAdvancedSliceWithLabel, messageApi]);
 
   const handleTabChange = (next: string) => {
+    if (document.activeElement instanceof HTMLElement) {
+      document.activeElement.blur();
+    }
     if (activeTabKey === 'advanced' && next !== 'advanced') {
       if (!applyAdvancedJsonToBasic()) return;
     }

frontend/src/pages/settings/SettingsPage.tsx

@@ -320,12 +320,14 @@ export default function SettingsPage() {
                     </Col>
 
                     <Col span={24}>
-                      <Tabs
-                        activeKey={activeTabKey}
-                        onChange={onTabChange}
-                        className={isMobile ? 'icons-only' : ''}
-                        items={tabItems}
-                      />
+                      <Card hoverable>
+                        <Tabs
+                          activeKey={activeTabKey}
+                          onChange={onTabChange}
+                          className={isMobile ? 'icons-only' : ''}
+                          items={tabItems}
+                        />
+                      </Card>
                     </Col>
                   </Row>
                 </>

frontend/src/pages/xray/BalancerFormModal.tsx

@@ -34,10 +34,10 @@ export default function BalancerFormModal({
   onConfirm,
 }: BalancerFormModalProps) {
   const { t } = useTranslation();
-  const [tag, setTag] = useState('');
-  const [strategy, setStrategy] = useState('random');
-  const [selector, setSelector] = useState<string[]>([]);
-  const [fallbackTag, setFallbackTag] = useState('');
+  const [tag, setTag] = useState(() => balancer?.tag || '');
+  const [strategy, setStrategy] = useState(() => balancer?.strategy || 'random');
+  const [selector, setSelector] = useState<string[]>(() => [...(balancer?.selector || [])]);
+  const [fallbackTag, setFallbackTag] = useState(() => balancer?.fallbackTag || '');
 
   const isEdit = balancer != null;
 
@@ -98,6 +98,7 @@ export default function BalancerFormModal({
       cancelText={t('close')}
       okButtonProps={{ disabled: !isValid }}
       mask={{ closable: false }}
+      destroyOnHidden
       onOk={submit}
       onCancel={onClose}
     >

frontend/src/pages/xray/OutboundFormModal.tsx

@@ -138,6 +138,9 @@ export default function OutboundFormModal({
   }
 
   function onTabChange(key: string) {
+    if (document.activeElement instanceof HTMLElement) {
+      document.activeElement.blur();
+    }
     if (revertingTabRef.current) {
       revertingTabRef.current = false;
       setActiveKey(key);

frontend/src/pages/xray/RoutingTab.tsx

@@ -76,7 +76,12 @@ export default function RoutingTab({
   const [editingIndex, setEditingIndex] = useState<number | null>(null);
   const [draggedIndex, setDraggedIndex] = useState<number | null>(null);
   const [dropTargetIndex, setDropTargetIndex] = useState<number | null>(null);
-  const dragStateRef = useRef<{ startY: number; moved: boolean }>({ startY: 0, moved: false });
+  const dragRef = useRef<{ from: number | null; to: number | null; startY: number; moved: boolean }>({
+    from: null,
+    to: null,
+    startY: 0,
+    moved: false,
+  });
 
   const rules = useMemo(
     () => (templateSettings?.routing?.rules || []) as RoutingRule[],
@@ -214,43 +219,49 @@ export default function RoutingTab({
   function onHandlePointerDown(idx: number, ev: React.PointerEvent) {
     if (ev.button != null && ev.button !== 0) return;
     ev.preventDefault();
+    try {
+      (ev.currentTarget as Element).setPointerCapture(ev.pointerId);
+    } catch { /* ignore */ }
+    dragRef.current = { from: idx, to: idx, startY: ev.clientY, moved: false };
     setDraggedIndex(idx);
     setDropTargetIndex(idx);
-    dragStateRef.current = { startY: ev.clientY, moved: false };
-    document.addEventListener('pointermove', onDragMove);
-    document.addEventListener('pointerup', onDragUp);
-    document.addEventListener('pointercancel', onDragUp);
-  }
-  function onDragMove(ev: PointerEvent) {
-    setDraggedIndex((dragged) => {
-      if (dragged == null) return dragged;
-      const state = dragStateRef.current;
-      if (!state.moved && Math.abs(ev.clientY - state.startY) < 5) return dragged;
+
+    const onMove = (e: PointerEvent) => {
+      const state = dragRef.current;
+      if (state.from == null) return;
+      if (!state.moved && Math.abs(e.clientY - state.startY) < 5) return;
       state.moved = true;
-      const el = document.elementFromPoint(ev.clientX, ev.clientY);
-      if (!el) return dragged;
+      const el = document.elementFromPoint(e.clientX, e.clientY);
+      if (!el) return;
       const target = el.closest('[data-row-key]');
-      if (!target) return dragged;
-      const idx = Number(target.getAttribute('data-row-key'));
-      if (Number.isFinite(idx)) setDropTargetIndex(idx);
-      return dragged;
-    });
-  }
-  function onDragUp() {
-    document.removeEventListener('pointermove', onDragMove);
-    document.removeEventListener('pointerup', onDragUp);
-    document.removeEventListener('pointercancel', onDragUp);
-    const from = draggedIndex;
-    const to = dropTargetIndex;
-    setDraggedIndex(null);
-    setDropTargetIndex(null);
-    if (!dragStateRef.current.moved || from == null || to == null || from === to) return;
-    mutate((tt) => {
-      const list = tt.routing?.rules;
-      if (!list) return;
-      const [moved] = list.splice(from, 1);
-      list.splice(to, 0, moved);
-    });
+      if (!target) return;
+      const newIdx = Number(target.getAttribute('data-row-key'));
+      if (Number.isFinite(newIdx) && newIdx !== state.to) {
+        state.to = newIdx;
+        setDropTargetIndex(newIdx);
+      }
+    };
+
+    const onUp = () => {
+      document.removeEventListener('pointermove', onMove);
+      document.removeEventListener('pointerup', onUp);
+      document.removeEventListener('pointercancel', onUp);
+      const { from, to, moved } = dragRef.current;
+      dragRef.current = { from: null, to: null, startY: 0, moved: false };
+      setDraggedIndex(null);
+      setDropTargetIndex(null);
+      if (!moved || from == null || to == null || from === to) return;
+      mutate((tt) => {
+        const list = tt.routing?.rules;
+        if (!list) return;
+        const [movedItem] = list.splice(from, 1);
+        list.splice(to, 0, movedItem);
+      });
+    };
+
+    document.addEventListener('pointermove', onMove);
+    document.addEventListener('pointerup', onUp);
+    document.addEventListener('pointercancel', onUp);
   }
 
   function ruleCriteriaChips(rule: RuleRow) {

frontend/src/pages/xray/XrayPage.tsx

@@ -305,6 +305,7 @@ export default function XrayPage() {
                   </Col>
 
                   <Col span={24}>
+                    <Card hoverable>
                     <Tabs
                       activeKey={activeTabKey}
                       onChange={onTabChange}
@@ -444,6 +445,7 @@ export default function XrayPage() {
                         },
                       ]}
                     />
+                    </Card>
                   </Col>
                 </Row>
               )}

frontend/src/utils/index.js

@@ -238,7 +238,7 @@ export class ObjectUtil {
     }
 
     static isArrEmpty(arr) {
-        return !this.isEmpty(arr) && arr.length === 0;
+        return !Array.isArray(arr) || arr.length === 0;
     }
 
     static copyArr(dest, src) {