fix: restore ayanamsa state and keep tests hermetic

scripts/cmd_muhurta.py

@@ -17,7 +17,7 @@ import os
 
 sys.path.insert(0, os.path.dirname(os.path.abspath(__file__)))
 
-from ayanamsa_utils import sidereal_flags
+from ayanamsa_utils import DEFAULT_AYANAMSA_NAME, sidereal_flags
 
 
 def _weekday_to_vara(py_weekday: int) -> int:
@@ -26,7 +26,7 @@ def _weekday_to_vara(py_weekday: int) -> int:
 
 
 def _get_sun_moon_lons(year: int, month: int, day: int,
-                       hour: int = 12, ayanamsa_name: str = 'lahiri') -> tuple:
+                       hour: int = 12, ayanamsa_name: str = DEFAULT_AYANAMSA_NAME) -> tuple:
     """获取太阳/月亮恒星黄经。优先 swisseph，退化为近似算法。"""
     def _primary_longitude(value):
         if isinstance(value, (list, tuple)):
@@ -112,7 +112,7 @@ def cmd_muhurta(args, chart_data: Optional[Dict] = None) -> int:
     hour_from_sunrise = getattr(args, 'hour_from_sunrise', 6.0)
     target_activity = getattr(args, 'activity', None)
     scan_days = getattr(args, 'scan_days', 1)
-    ayanamsa_name = getattr(args, 'ayanamsa', 'lahiri')
+    ayanamsa_name = getattr(args, 'ayanamsa', None) or DEFAULT_AYANAMSA_NAME
 
     activities = list(ACTIVITY_RULES.keys())
     if target_activity and target_activity not in activities: