feat: add OI long-term collection script for cron-based data accumulation

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

scripts/collect_oi.py

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+"""
+OI 장기 수집 스크립트.
+15분마다 cron 실행하여 Binance OI를 data/oi_history.parquet에 누적한다.
+
+사용법:
+  python scripts/collect_oi.py
+  python scripts/collect_oi.py --symbol XRPUSDT
+
+crontab 예시:
+  */15 * * * * cd /path/to/cointrader && .venv/bin/python scripts/collect_oi.py >> logs/collect_oi.log 2>&1
+"""
+import sys
+from pathlib import Path
+sys.path.insert(0, str(Path(__file__).parent.parent))
+
+import argparse
+from datetime import datetime, timezone
+
+import pandas as pd
+from binance.client import Client
+from dotenv import load_dotenv
+import os
+
+load_dotenv()
+
+OI_PATH = Path("data/oi_history.parquet")
+
+
+def collect(symbol: str = "XRPUSDT"):
+    client = Client(
+        api_key=os.getenv("BINANCE_API_KEY", ""),
+        api_secret=os.getenv("BINANCE_API_SECRET", ""),
+    )
+
+    result = client.futures_open_interest(symbol=symbol)
+    oi_value = float(result["openInterest"])
+    ts = datetime.now(timezone.utc)
+
+    new_row = pd.DataFrame([{
+        "timestamp": ts,
+        "symbol": symbol,
+        "open_interest": oi_value,
+    }])
+
+    if OI_PATH.exists():
+        existing = pd.read_parquet(OI_PATH)
+        combined = pd.concat([existing, new_row], ignore_index=True)
+    else:
+        OI_PATH.parent.mkdir(parents=True, exist_ok=True)
+        combined = new_row
+
+    combined.to_parquet(OI_PATH, index=False)
+    print(f"[{ts.isoformat()}] OI={oi_value:.2f} → {OI_PATH}")
+
+
+def main():
+    parser = argparse.ArgumentParser(description="OI 장기 수집")
+    parser.add_argument("--symbol", default="XRPUSDT")
+    args = parser.parse_args()
+    collect(symbol=args.symbol)
+
+
+if __name__ == "__main__":
+    main()