feat: add ADX calculation to indicators

Add ADX (Average Directional Index) with period 14 to calculate_all()
for sideways market filtering. Includes test verifying the adx column
exists and contains non-negative values.

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

src/indicators.py

@@ -43,6 +43,10 @@ class Indicators:
         df["stoch_k"] = stoch["STOCHRSIk_14_14_3_3"]
         df["stoch_d"] = stoch["STOCHRSId_14_14_3_3"]
 
+        # ADX (14) — 횡보장 필터
+        adx_df = ta.adx(df["high"], df["low"], df["close"], length=14)
+        df["adx"] = adx_df["ADX_14"]
+
         # 거래량 이동평균
         df["vol_ma20"] = ta.sma(df["volume"], length=20)
 

tests/test_indicators.py

@@ -45,6 +45,15 @@ def test_bollinger_bands(sample_df):
     assert (valid["bb_upper"] >= valid["bb_lower"]).all()
 
 
+def test_adx_column_exists(sample_df):
+    """calculate_all()이 adx 컬럼을 생성하는지 확인."""
+    ind = Indicators(sample_df)
+    df = ind.calculate_all()
+    assert "adx" in df.columns
+    valid = df["adx"].dropna()
+    assert (valid >= 0).all()
+
+
 def test_signal_returns_direction(sample_df):
     ind = Indicators(sample_df)
     df = ind.calculate_all()