Add React frontend for energy trading system

Implements React + TypeScript UI with Vite and Tailwind CSS.
Features dashboard with real-time WebSocket updates, backtesting
page, model management interface, trading controls, and settings.
Includes state management with Zustand, API integration with
Axios/TanStack Query, and interactive charts with Recharts.

frontend/src/hooks/useWebSocket.ts

@@ -0,0 +1,21 @@
+import { useEffect } from 'react';
+import { webSocketService } from '@/services/websocket';
+import type { WebSocketEventType } from '@/services/types';
+
+export function useWebSocket() {
+  useEffect(() => {
+    webSocketService.connect();
+    return () => webSocketService.disconnect();
+  }, []);
+
+  const subscribe = <T = unknown>(
+    eventType: WebSocketEventType,
+    handler: (data: T) => void
+  ): (() => void) => {
+    return webSocketService.subscribe<T>(eventType, handler);
+  };
+
+  const isConnected = webSocketService.getConnectionStatus();
+
+  return { subscribe, isConnected };
+}