feat(lotto): run_forward_purchase 3전략 구매·채점·저장

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

lotto/tests/test_backtest_db.py

@@ -90,6 +90,22 @@ def test_backfill_calibration_idempotent(monkeypatch):
     assert r3["calibrated"] == 0
 
 
+def test_run_forward_purchase_persists_all_strategies(monkeypatch):
+    db = _fresh_db(monkeypatch)
+    _seed_draws(db, 40)
+    from app import backtest as bt
+    # 작은 규모로 빠르게
+    res = bt.run_forward_purchase(draw_no=40, k=20, pool_n=500, sample_seed=5)
+    assert res["ok"] is True
+    rows = db.get_backtest_runs(draw_no=40)
+    strategies = {r["strategy"] for r in rows}
+    assert "random_null" in strategies
+    assert "coverage" in strategies
+    assert "engine_w" in strategies   # base 가중치로 최소 1건
+    for r in rows:
+        assert r["n_tickets"] == 20
+
+
 def test_get_calibrated_draw_nos(monkeypatch):
     """저장된 draw_no 집합이 get_calibrated_draw_nos에 포함되어야 한다."""
     db = _fresh_db(monkeypatch)