fix: persist sell prices to DB and add WF filter bootstrap

- price_db: add sell_prices table (ensure/upsert/load/delete)
- trader: restore _last_sell_prices from DB on startup so re-entry
  block survives restarts; persist each sell price immediately
- market: retry chunk requests up to 3 times with backoff on 429

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

core/price_db.py

@@ -196,6 +196,56 @@ def load_recent_wins(ticker: str, n: int = 5) -> list[bool]:
     return [bool(r[0]) for r in rows]
 
 
+# ── 직전 매도가 영구 저장 (재시작 후 재매수 차단 유지용) ──────────────────────
+
+def ensure_sell_prices_table() -> None:
+    """sell_prices 테이블이 없으면 생성."""
+    ddl = """
+        CREATE TABLE sell_prices (
+            ticker     VARCHAR2(20) NOT NULL PRIMARY KEY,
+            price      NUMBER(20,8) NOT NULL,
+            updated_at TIMESTAMP    DEFAULT SYSTIMESTAMP NOT NULL
+        )
+    """
+    with _conn() as conn:
+        try:
+            conn.cursor().execute(ddl)
+        except oracledb.DatabaseError as e:
+            if e.args[0].code != 955:  # ORA-00955: 이미 존재
+                raise
+
+
+def upsert_sell_price(ticker: str, price: float) -> None:
+    """직전 매도가 저장 또는 갱신."""
+    sql = """
+        MERGE INTO sell_prices s
+        USING (SELECT :ticker AS ticker FROM dual) d
+        ON (s.ticker = d.ticker)
+        WHEN MATCHED THEN
+            UPDATE SET price = :price, updated_at = SYSTIMESTAMP
+        WHEN NOT MATCHED THEN
+            INSERT (ticker, price) VALUES (:ticker, :price)
+    """
+    with _conn() as conn:
+        conn.cursor().execute(sql, {"ticker": ticker, "price": price})
+
+
+def load_sell_prices() -> dict[str, float]:
+    """저장된 직전 매도가 전체 로드."""
+    with _conn() as conn:
+        cur = conn.cursor()
+        cur.execute("SELECT ticker, price FROM sell_prices")
+        return {r[0]: float(r[1]) for r in cur.fetchall()}
+
+
+def delete_sell_price(ticker: str) -> None:
+    """매도가 기록 삭제 (더 이상 필요 없을 때)."""
+    with _conn() as conn:
+        conn.cursor().execute(
+            "DELETE FROM sell_prices WHERE ticker = :ticker", {"ticker": ticker}
+        )
+
+
 def load_positions() -> list[dict]:
     """저장된 전체 포지션 로드."""
     sql = """