fix: use nakshatra seed for Yogini dasha (upstream cb7fe017)

(nakshatra + 3) mod 8 seed. The upstream edit to
tests/test_dasha_master_pack_coverage.py is dropped: that file does not
exist here. TASK-upstream-sync5-20261002 U5.

(cherry picked from commit cb7fe017)

Co-Authored-By: Claude Opus 5.5 (1M context) <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01N4f2nya58RoRu4yEmJgRGE

scripts/yogini_dasha.py

@@ -23,16 +23,9 @@ The 8 Yoginis, their year allotments, and associated planets:
 Total: 1 + 2 + 3 + 4 + 5 + 6 + 7 + 8 = 36 years.
 
 Starting Yogini:
-    The starting Yogini is determined by the Ascendant (Lagna) Rashi.
-    Per standard texts:
-        - Aries / Leo / Sagittarius / Gemini / Libra / Aquarius
-          → start from Maya (1)
-        - Taurus / Virgo / Capricorn / Cancer / Scorpio / Pisces
-          → start from Bhadrika (2)
-
-    Alternative (more common) rule based on Lagna degree modulo 8:
-        Lagna Nakshatra Pada determines the starting Yogini.
-        For simplicity, this implementation uses the Ascendant Rashi rule above.
+    When the Moon's nakshatra index is supplied, use the standard
+    ``(nakshatra_index + 3) mod 8`` seed. The older Lagna-rashi seed remains
+    an explicit compatibility fallback when no Moon nakshatra is available.
 
 Reference: Various classical and modern Jyotish texts on Yogini Dasha.
 """
@@ -113,6 +106,7 @@ def calculate_yogini_dasha(birth_info: dict) -> dict:
         birth_info: dict containing:
             - "lagna_rashi_index": int (0 = Aries, ..., 11 = Pisces)
             - "birth_datetime": datetime object or ISO-format string (optional)
+            - "moon_nakshatra_index": 0-based nakshatra index (optional)
 
     Returns:
         dict with keys:
@@ -130,7 +124,14 @@ def calculate_yogini_dasha(birth_info: dict) -> dict:
     if birth_dt is None:
         birth_dt = datetime.now()
 
-    start_idx = _get_start_yogini_index(lagna_idx)
+    moon_nakshatra_index = birth_info.get("moon_nakshatra_index")
+    if moon_nakshatra_index is not None:
+        moon_nakshatra_index = int(moon_nakshatra_index) % 27
+        start_idx = (moon_nakshatra_index + 3) % 8
+        seed_method = 'moon_nakshatra_plus_3_mod_8'
+    else:
+        start_idx = _get_start_yogini_index(lagna_idx)
+        seed_method = 'legacy_lagna_rashi_compatibility'
     starting_yogini = YOGINI_SEQUENCE[start_idx]["name"]
     starting_planet = YOGINI_SEQUENCE[start_idx]["planet"]
 
@@ -163,6 +164,7 @@ def calculate_yogini_dasha(birth_info: dict) -> dict:
         "total_cycle": TOTAL_CYCLE,
         "starting_yogini": starting_yogini,
         "starting_planet": starting_planet,
+        "seed_method": seed_method,
     }