chore(repo): initialize Cowork Local Gitea repository

core/holiday_calendar.py

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+"""Public-holiday lookup by country for Schedule Task's "skip holidays".
+
+Prefers the ``holidays`` PyPI package (200+ countries, correct lunar-calendar
+dates for Tết etc.). If it isn't installed or the country code is unknown,
+falls back to a small built-in fixed-date table (VN/JP national days only) so
+the feature degrades gracefully instead of crashing offline installs.
+"""
+from __future__ import annotations
+
+from datetime import date
+from typing import Dict, Optional, Set, Tuple
+
+# Country codes offered in the task editor (any ISO code typed in still works
+# when the `holidays` package is installed).
+COMMON_COUNTRIES = ("VN", "JP", "US", "KR", "CN", "SG", "DE", "FR", "GB", "IN")
+
+# Fixed-date fallback (month, day) — used only when the holidays package is
+# unavailable. Lunar holidays (Tết, Hùng Kings…) can't be fixed dates, so the
+# fallback intentionally covers solar-calendar national days only.
+_FALLBACK: Dict[str, Set[Tuple[int, int]]] = {
+    "VN": {(1, 1), (4, 30), (5, 1), (9, 2)},
+    "JP": {(1, 1), (2, 11), (2, 23), (4, 29), (5, 3), (5, 4), (5, 5),
+           (8, 11), (11, 3), (11, 23)},
+}
+
+_cache: Dict[Tuple[str, int], object] = {}
+
+
+def _package_calendar(country: str, year: int):
+    """A holidays-package calendar for (country, year), cached; None when the
+    package is missing or the country code is unknown to it."""
+    key = (country, year)
+    if key in _cache:
+        return _cache[key]
+    cal = None
+    try:
+        import holidays as _holidays
+
+        cal = _holidays.country_holidays(country, years=[year, year + 1])
+    except Exception:   # noqa: BLE001 — package missing / unknown country code
+        cal = None
+    _cache[key] = cal
+    return cal
+
+
+def is_holiday(d: date, country: Optional[str]) -> bool:
+    country = (country or "").strip().upper()
+    if not country:
+        return False
+    cal = _package_calendar(country, d.year)
+    if cal is not None:
+        return d in cal
+    return (d.month, d.day) in _FALLBACK.get(country, set())