Add FastAPI backend for energy trading system

Implements FastAPI backend with ML model support for energy trading,
including price prediction models and RL-based battery trading policy.
Features dashboard, trading, backtest, and settings API routes with
WebSocket support for real-time updates.

backend/app/services/trading_service.py

@@ -0,0 +1,61 @@
+from typing import Dict, List, Optional
+from datetime import datetime
+from app.utils.logger import get_logger
+
+logger = get_logger(__name__)
+
+
+class TradingPosition:
+    timestamp: datetime
+    position_type: str
+    region: Optional[str]
+    volume_mw: float
+    entry_price: float
+    current_price: float
+    pnl: float
+
+
+class TradingService:
+    def __init__(self):
+        self._positions: List[Dict] = []
+        self._orders: List[Dict] = []
+
+    async def get_positions(self) -> List[Dict]:
+        return self._positions.copy()
+
+    async def get_orders(self, limit: int = 100) -> List[Dict]:
+        return self._orders[-limit:]
+
+    async def place_order(self, order: Dict) -> Dict:
+        order_id = f"order_{len(self._orders) + 1}"
+        order["order_id"] = order_id
+        order["timestamp"] = datetime.utcnow()
+        order["status"] = "filled"
+
+        self._orders.append(order)
+
+        logger.info(f"Order placed: {order_id}, type: {order.get('type')}, volume: {order.get('volume_mw')}")
+
+        return order
+
+    async def close_position(self, position_id: str) -> Dict:
+        for i, pos in enumerate(self._positions):
+            if pos.get("position_id") == position_id:
+                position = self._positions.pop(i)
+                position["closed_at"] = datetime.utcnow()
+                position["status"] = "closed"
+                logger.info(f"Position closed: {position_id}")
+                return position
+
+        raise ValueError(f"Position not found: {position_id}")
+
+    async def get_trading_summary(self) -> Dict:
+        total_pnl = sum(pos.get("pnl", 0) for pos in self._positions)
+        open_positions = len([p for p in self._positions if p.get("status") == "open"])
+
+        return {
+            "total_pnl": total_pnl,
+            "open_positions": open_positions,
+            "total_trades": len(self._orders),
+            "last_trade": self._orders[-1]["timestamp"] if self._orders else None,
+        }