fix(admin): 日期组件进入界面后应滚动到当前日期/选中项居中

AdminDatePicker:
- scrollToDateElement 在 props.modelValue 为空时回退到今天
- onMounted: 空值时走 smooth(有滚动感)，有值走 auto(无声定位)，不再直接 return 停在最左

AdminMultiDatePicker:
- 新增 scrollToDateElement 通用 + watch(modelValue)
- onMounted 分两支: 有选中值时跳到首个 >= 今天的选中项 否则跳今天
- 目标超出 dateRange 时先扩 range 再滚 (避免定位不到元素)

app/components/Admin/AdminDatePicker.vue

@@ -239,10 +239,12 @@ const selectDate = (dateValue) => {
   emit('change', dateValue)
 }
 
-const scrollToDateElement = (behavior = 'smooth') => {
-  if (!dateSelector.value || !props.modelValue) return
-  const el = dateSelector.value.querySelector(`[data-date="${props.modelValue}"]`)
-  if (el) el.scrollIntoView({ behavior, block: 'nearest', inline: 'center' })
+const scrollToDateElement = (behavior = 'smooth', targetDate = props.modelValue) => {
+  if (!dateSelector.value) return
+  const dateKey = targetDate || formatDateStr(today)
+  const el = dateSelector.value.querySelector(`[data-date="${dateKey}"]`)
+  if (!el) return
+  el.scrollIntoView({ behavior, block: 'nearest', inline: 'center' })
 }
 
 const handleWheel = (event) => {
@@ -324,7 +326,7 @@ watch(() => props.modelValue, () => {
 })
 
 onMounted(() => {
-  nextTick(() => scrollToDateElement('auto'))
+  nextTick(() => scrollToDateElement(props.modelValue ? 'auto' : 'smooth'))
 })
 </script>