feat(holiday-settings): implement organization holiday settings management

- Added SQL migration for creating organization holiday settings and state holidays tables with necessary constraints and indexes.
- Implemented API endpoints in AdminCenterController for retrieving and updating organization holiday settings.
- Updated admin-center API router to include routes for holiday settings management.
- Enhanced localization files to support new holiday settings UI elements in multiple languages.
- Improved holiday calendar component to display working days and integrate holiday settings.

worklenz-frontend/public/locales/zh/admin-center/overview.json

@@ -28,5 +28,45 @@
   "manDaysCalculationDescription": "所有项目成本将使用估算人天数 × 日费率计算",
   "calculationMethodTooltip": "此设置适用于您组织中的所有项目",
   "calculationMethodUpdated": "组织计算方法更新成功",
-  "calculationMethodUpdateError": "更新计算方法失败"
+  "calculationMethodUpdateError": "更新计算方法失败",
+  "holidayCalendar": "假期日历",
+  "addHoliday": "添加假期",
+  "editHoliday": "编辑假期",
+  "holidayName": "假期名称",
+  "holidayNameRequired": "请输入假期名称",
+  "description": "描述",
+  "date": "日期",
+  "dateRequired": "请选择日期",
+  "holidayType": "假期类型",
+  "holidayTypeRequired": "请选择假期类型",
+  "recurring": "循环",
+  "save": "保存",
+  "update": "更新",
+  "cancel": "取消",
+  "holidayCreated": "假期创建成功",
+  "holidayUpdated": "假期更新成功",
+  "holidayDeleted": "假期删除成功",
+  "errorCreatingHoliday": "创建假期时出错",
+  "errorUpdatingHoliday": "更新假期时出错",
+  "errorDeletingHoliday": "删除假期时出错",
+  "importCountryHolidays": "导入国家假期",
+  "country": "国家",
+  "countryRequired": "请选择国家",
+  "selectCountry": "选择国家",
+  "year": "年份",
+  "import": "导入",
+  "holidaysImported": "成功导入{{count}}个假期",
+  "errorImportingHolidays": "导入假期时出错",
+  "addCustomHoliday": "添加自定义假期",
+  "officialHolidaysFrom": "官方假期来自",
+  "workingDay": "工作日",
+  "holiday": "假期",
+  "today": "今天",
+  "cannotEditOfficialHoliday": "无法编辑官方假期",
+  "customHoliday": "自定义假期",
+  "officialHoliday": "官方假期",
+  "delete": "删除",
+  "deleteHolidayConfirm": "您确定要删除这个假期吗？",
+  "yes": "是",
+  "no": "否"
 }