fix(date-picker): fix the issue of incorrect month synchronization on the right panel (#6204)

* Initial plan

* Changes before error encountered

Co-authored-by: liweijie0812 <[email protected]>

* chore: stash changelog [ci skip]

* chore: stash changelog [ci skip]

---------

Co-authored-by: copilot-swe-agent[bot] <[email protected]>
Co-authored-by: liweijie0812 <[email protected]>
Co-authored-by: tdesign-bot <[email protected]>

Author: 3 people

packages/components/date-picker/hooks/useRangeValue.ts

@@ -67,7 +67,8 @@ export function useRangeValue(props: TdDateRangePickerProps) {
       if (year.value[1] < year.value[0]) {
         year.value[1] = year.value[0];
       }
-      if (month.value[1] < month.value[0]) {
+      // 只有当左右面板年份相同时，才需要比较月份大小
+      if (year.value[0] === year.value[1] && month.value[1] < month.value[0]) {
         month.value[1] = month.value[0];
       }
     },

packages/tdesign-vue-next/.changelog/pr-6204.md

@@ -0,0 +1,6 @@
+---
+pr_number: 6204
+contributor: Copilot
+---
+
+- fix(date-picker): 修复日期区间选择器跨年时右侧面板月份错误同步的问题 @liweijie0812 @Copilot ([#6204](https://github.com/Tencent/tdesign-vue-next/pull/6204))