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/main.py

@@ -0,0 +1,68 @@
+from fastapi import FastAPI, WebSocket, WebSocketDisconnect
+from fastapi.middleware.cors import CORSMiddleware
+from app.config import settings
+from app.utils.logger import setup_logger, get_logger
+from app.api.routes import dashboard, backtest, models, trading, settings as settings_routes
+from app.api.websocket import manager
+
+setup_logger()
+logger = get_logger(__name__)
+
+app = FastAPI(
+    title=settings.APP_NAME,
+    version=settings.APP_VERSION,
+    docs_url="/docs",
+    redoc_url="/redoc",
+)
+
+app.add_middleware(
+    CORSMiddleware,
+    allow_origins=settings.cors_origins_list,
+    allow_credentials=True,
+    allow_methods=["*"],
+    allow_headers=["*"],
+)
+
+app.include_router(dashboard.router, prefix="/api/v1/dashboard", tags=["dashboard"])
+app.include_router(backtest.router, prefix="/api/v1/backtest", tags=["backtest"])
+app.include_router(models.router, prefix="/api/v1/models", tags=["models"])
+app.include_router(trading.router, prefix="/api/v1/trading", tags=["trading"])
+app.include_router(settings_routes.router, prefix="/api/v1/settings", tags=["settings"])
+
+
+@app.on_event("startup")
+async def startup_event():
+    logger.info(f"Starting {settings.APP_NAME} v{settings.APP_VERSION}")
+    logger.info(f"Data path: {settings.DATA_PATH_RESOLVED}")
+
+
+@app.on_event("shutdown")
+async def shutdown_event():
+    logger.info("Shutting down application")
+
+
+@app.get("/health")
+async def health_check():
+    return {"status": "healthy", "version": settings.APP_VERSION}
+
+
+@app.websocket("/ws/real-time")
+async def websocket_endpoint(websocket: WebSocket):
+    await manager.connect(websocket)
+    try:
+        while True:
+            data = await websocket.receive_text()
+            await manager.broadcast("message", {"text": data})
+    except WebSocketDisconnect:
+        manager.disconnect(websocket)
+
+
+if __name__ == "__main__":
+    import uvicorn
+
+    uvicorn.run(
+        "app.main:app",
+        host=settings.HOST,
+        port=settings.PORT,
+        reload=settings.DEBUG,
+    )