fix: restore positions on restart and fix notify env loading

- restore_positions(): read Upbit balances on startup to prevent
  double-buying after restart
- notify.py: read TOKEN/CHAT_ID inside _send() to avoid empty values
  when module is imported before load_dotenv()

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

core/trader.py

@@ -39,6 +39,38 @@ def get_positions() -> dict:
     return _positions
 
 
+def restore_positions() -> None:
+    """시작 시 Upbit 실제 잔고를 읽어 포지션 복원 (재시작 이중 매수 방지)."""
+    upbit = _get_upbit()
+    balances = upbit.get_balances()
+    for b in balances:
+        currency = b["currency"]
+        if currency == "KRW":
+            continue
+        amount = float(b["balance"]) + float(b["locked"])
+        if amount <= 0:
+            continue
+        ticker = f"KRW-{currency}"
+        current = pyupbit.get_current_price(ticker)
+        if not current:
+            continue
+        invested_krw = int(amount * current)
+        if invested_krw < 1_000:  # 소액 잔고 무시
+            continue
+        with _lock:
+            _positions[ticker] = {
+                "buy_price": current,   # 정확한 매수가 불명 → 현재가로 초기화
+                "peak_price": current,
+                "amount": amount,
+                "invested_krw": min(invested_krw, PER_POSITION),
+                "entry_time": datetime.now(),
+            }
+        logger.info(
+            f"[복원] {ticker} 수량={amount} | 현재가={current:,.0f}원 "
+            f"(재시작 시 복원, 매수가 불명으로 현재가 기준)"
+        )
+
+
 def buy(ticker: str) -> bool:
     """시장가 매수. 예산·포지션 수 확인 후 진입."""
     with _lock: