feat: Enhance trading system with new e_min_chg_pct parameter and related logic

Changes:
- Introduced the `e_min_chg_pct` parameter to define the minimum price change percentage compared to the previous day's close, enhancing the momentum trading strategy.
- Updated various functions and classes to incorporate this new parameter, ensuring it is utilized in both backtesting and live trading scenarios.
- Improved documentation and comments to clarify the purpose and usage of the new parameter across the codebase.

Impact:
- This addition allows for more precise control over trading conditions, potentially increasing the effectiveness of the momentum strategy while maintaining system integrity and performance.

kis_trader/backtest/breakout_backtest_common.py

@@ -344,7 +344,12 @@ def load_breakout_candles_by_code(
     *,
     history_source: str = "kiwoom",
 ) -> Tuple[Dict[str, List[Dict]], int]:
-    """1분봉 전 종목 로드. history_source=ls → ls_ws_candles."""
+    """1분봉 전 종목 로드. history_source=ls → ls_ws_candles.
+
+    반환은 ``(candles_by_code, total_rows)`` 만 — 호출부에서 ``codes`` 리스트를
+    만들지 않는다. 웹 응답용 종목 수는 ``_codes_from_candles_map`` 으로 바인딩.
+    (LS/키움 테이블만 다르고 dict 키 스키마는 동일)
+    """
     min_bars = breakout_min_bars_required({
         "lookback_min": lookback_min,
         "vol_window": int(vol_window),