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/__init__.py

@@ -0,0 +1,7 @@
+from fastapi import FastAPI
+from app.config import settings
+from app.utils.logger import get_logger
+
+logger = get_logger(__name__)
+
+__all__ = ["app", "settings", "logger"]