feat(calendar): show regional holidays and observances

public/locales/zh-CN.json

@@ -367,7 +367,47 @@
     "emptyDay": "这一天还没有记忆或目标节点。",
     "openToday": "写下一段记忆",
     "writeMemory": "新增记忆",
-    "openTasks": "打开待办"
+    "openTasks": "打开待办",
+    "holidayCountry": "国家或地区",
+    "autoCountry": "自动（{country}）",
+    "publicHoliday": "公共假期",
+    "festival": "节日",
+    "workingDay": "工作日",
+    "observed": "补休",
+    "estimated": "日期待确认",
+    "workingWeekend": "调休补班",
+    "loadingHolidays": "正在加载节假日…",
+    "holidayUnavailable": "节假日数据暂不可用。",
+    "retryHolidays": "重试",
+    "holidaySource": "公共假期数据",
+    "outsideRange": "节假日数据覆盖 2024—2030 年。",
+    "festivals": {
+      "valentine": "情人节",
+      "earth": "世界地球日",
+      "halloween": "万圣节",
+      "christmasEve": "平安夜",
+      "teachers": "教师节"
+    },
+    "holidayNames": {
+      "New Year's Day": "元旦",
+      "Chinese New Year (Spring Festival)": "春节",
+      "Chinese New Year": "春节",
+      "Chinese New Year's Eve": "除夕",
+      "Tomb-Sweeping Day": "清明节",
+      "Labor Day": "劳动节",
+      "Dragon Boat Festival": "端午节",
+      "Mid-Autumn Festival": "中秋节",
+      "National Day": "国庆节",
+      "Christmas Day": "圣诞节",
+      "Christmas Eve": "平安夜",
+      "Good Friday": "耶稣受难日",
+      "Easter Monday": "复活节星期一",
+      "Peace Memorial Day": "和平纪念日",
+      "Children's Day": "儿童节",
+      "Constitution Day": "行宪纪念日",
+      "Confucius' Birthday": "孔子诞辰"
+    },
+    "holidayCaveat": "日期可能调整，请以当地官方公告为准。"
   },
   "tasks": {
     "eyebrow": "目标与待办",