feat(lotto): curator_helpers — 후보 병합·피처·맥락

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

backend/app/purchase_manager.py

@@ -97,3 +97,18 @@ def check_purchases_for_draw(drw_no: int) -> int:
 
     logger.info(f"[purchase_manager] {drw_no}회차 구매 {count}건 체크 완료")
     return count
+
+
+def get_recent_performance(limit: int = 3) -> list:
+    """최근 N회차 내 구매 성과 요약. 없으면 빈 리스트."""
+    from . import db
+    purchases = db.get_purchases(days=None) or []
+    by_draw: dict = {}
+    for p in purchases:
+        d = p.get("draw_no")
+        if not d:
+            continue
+        by_draw.setdefault(d, {"draw_no": d, "purchased_sets": 0, "best_match": 0})
+        by_draw[d]["purchased_sets"] += int(p.get("sets") or 1)
+        by_draw[d]["best_match"] = max(by_draw[d]["best_match"], int(p.get("correct_count") or 0))
+    return sorted(by_draw.values(), key=lambda x: -x["draw_no"])[:limit]