feat: 新增节假日缓存，仅工作日生成与推送

- daily/holiday.py: 抓取 xiaoai.me 全年节假日并缓存到 .cache/holidays-<year>.json，
  is_workday() 判定（法定节假日/周末休息，调休补班日上班），联网失败回退本地缓存
- scheduler: tick_once 前置工作日闸门，非工作日标记完成并跳过，判定失败降级为正常工作日避免漏跑
- config/.env.example: 新增 DAILY_WORKDAY_ONLY 开关（默认开）
- tests: test_holiday 8 例 + scheduler 非工作日闸门 2 例

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

tests/test_holiday.py

@@ -0,0 +1,57 @@
+"""Tests for daily.holiday."""
+
+from __future__ import annotations
+
+import unittest
+from datetime import date
+
+from daily.holiday import is_workday, workday_name
+
+# 模拟 2026 节假日表：1/1 元旦(休)，1/4 元旦调休(补班)
+HOLIDAYS = {
+    "2026-01-01": {"rest": True, "name": "元旦节"},
+    "2026-01-02": {"rest": True, "name": "元旦节"},
+    "2026-01-03": {"rest": True, "name": "元旦节"},
+    "2026-01-04": {"rest": False, "name": "元旦节调休"},
+    "2026-02-16": {"rest": True, "name": "春节"},
+    "2026-02-14": {"rest": False, "name": "春节调休"},
+}
+
+
+class IsWorkdayTests(unittest.TestCase):
+    def test_legal_holiday_is_rest(self):
+        # 2026-01-01 周四，元旦 → 休息
+        self.assertFalse(is_workday(date(2026, 1, 1), HOLIDAYS))
+
+    def test_tiaoxiu_makeup_day_is_workday(self):
+        # 2026-01-04 周日，调休补班 → 上班
+        self.assertEqual(date(2026, 1, 4).weekday(), 6)
+        self.assertTrue(is_workday(date(2026, 1, 4), HOLIDAYS))
+
+    def test_spring_festival_holiday(self):
+        self.assertFalse(is_workday(date(2026, 2, 16), HOLIDAYS))
+
+    def test_spring_festival_makeup_saturday(self):
+        # 2026-02-14 周六，调休 → 上班
+        self.assertEqual(date(2026, 2, 14).weekday(), 5)
+        self.assertTrue(is_workday(date(2026, 2, 14), HOLIDAYS))
+
+    def test_normal_weekday(self):
+        # 2026-07-23 周四，非节假日 → 上班
+        self.assertTrue(is_workday(date(2026, 7, 23), HOLIDAYS))
+
+    def test_normal_weekend(self):
+        # 2026-07-25 周六，非节假日 → 休息
+        self.assertFalse(is_workday(date(2026, 7, 25), HOLIDAYS))
+
+
+class WorkdayNameTests(unittest.TestCase):
+    def test_holiday_name(self):
+        self.assertEqual(workday_name(date(2026, 1, 1), HOLIDAYS), "元旦节")
+
+    def test_normal_day_has_no_name(self):
+        self.assertIsNone(workday_name(date(2026, 7, 23), HOLIDAYS))
+
+
+if __name__ == "__main__":
+    unittest.main()

tests/test_scheduler.py

@@ -4,6 +4,7 @@ from __future__ import annotations
 
 import unittest
 from datetime import datetime
+from unittest import mock
 from zoneinfo import ZoneInfo
 
 from daily.scheduler import (
@@ -12,6 +13,7 @@ from daily.scheduler import (
     next_occurrence_after,
     parse_hhmm,
     plan_next_action,
+    tick_once,
 )
 
 
@@ -116,3 +118,39 @@ class NextOccurrenceTests(unittest.TestCase):
         nxt = next_occurrence_after(ClockTime(8, 50), tz, now)
         self.assertEqual(nxt.date().isoformat(), "2026-07-10")
         self.assertEqual((nxt.hour, nxt.minute), (8, 50))
+
+
+class WorkdayGateTests(unittest.TestCase):
+    """非工作日 tick_once 直接标记完成并跳过，不触发 generate。"""
+
+    def setUp(self) -> None:
+        self.tz = ZoneInfo("Asia/Shanghai")
+        self.gen = ClockTime(8, 50)
+        self.push = ClockTime(9, 0)
+
+    def _tick(self, day, workday):
+        now = datetime(day.year, day.month, day.day, 8, 30, tzinfo=self.tz)
+        holidays = {} if workday else {day.isoformat(): {"rest": True, "name": "测试假"}}
+        with mock.patch("daily.scheduler.load_holidays", return_value=holidays), \
+             mock.patch("daily.scheduler.run_scheduled_action") as run:
+            state = tick_once(
+                now=now, tz=self.tz, state=SchedulerState(),
+                generate_at=self.gen, push_at=self.push, dry_run=True,
+            )
+        return state, run
+
+    def test_holiday_skips_and_marks_done(self):
+        # 2026-07-25 是周六；强制为非工作日
+        from datetime import date
+        day = date(2026, 7, 25)
+        state, run = self._tick(day, workday=False)
+        self.assertFalse(run.called)
+        self.assertEqual(state.last_generate_date, "2026-07-25")
+        self.assertEqual(state.last_push_date, "2026-07-25")
+
+    def test_workday_proceeds(self):
+        from datetime import date
+        day = date(2026, 7, 23)  # 周四，工作日
+        state, run = self._tick(day, workday=True)
+        # 工作日不提前标记完成（dry-run 不执行动作，故 last_generate_date 仍为 None）
+        self.assertIsNone(state.last_generate_date)