feat(lotto): calibrate_winner_compute 당첨조합 역분석+percentile

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

lotto/app/backtest.py

@@ -91,6 +91,20 @@ def point_in_time_draws(draws: List[Tuple[int, List[int]]],
     return [(d, nums) for d, nums in draws if d < target_draw_no]
 
 
+def calibrate_winner_compute(draws, target_draw_no, winning6,
+                             sample_m: int = 2000, seed: Optional[int] = None) -> Dict[str, Any]:
+    """순수 연산: point-in-time 캐시로 당첨조합 채점 + 무작위 M표본 percentile."""
+    pit = point_in_time_draws(draws, target_draw_no)
+    cache = build_analysis_cache(pit)
+    scores = score_combination(sorted(winning6), cache)
+    win_total = scores["score_total"]
+    samples = random_null_tickets(sample_m, seed=seed)
+    le = sum(1 for t in samples
+             if score_combination(t, cache)["score_total"] <= win_total)
+    percentile = le / max(len(samples), 1)
+    return {"scores": scores, "percentile": percentile, "cache_draws": len(pit)}
+
+
 def coverage_tickets(k: int, seed: Optional[int] = None) -> List[List[int]]:
     """greedy 커버리지 — 아직 덜 쓰인 번호를 우선 배치해 번호를 넓게 분산.
     (휠링/보장설계는 향후. 현재는 distinct + 번호 사용 균등화)"""