feat: Complete frontend-backend integration with JWT authentication

- Integrated React frontend with FastAPI backend
- Implemented JWT token-based authentication
- Created all dashboard pages (Trading, Portfolio, Backtest, etc.)
- Fixed API client with proper error handling
- Added environment variable configuration
- Connected all routes and endpoints
- Added comprehensive documentation

Frontend:
- Modern React + TypeScript UI with Vite
- All pages working: Dashboard, Trading, Portfolio, Backtest, Cash, Watchlists, Alerts
- Protected routes with auto-redirect
- JWT token management in localStorage
- Proper error handling and user feedback

Backend:
- FastAPI with async SQLAlchemy
- JWT authentication system
- All API endpoints functional
- CORS properly configured
- Database models and schemas updated

Test user: demo@quantresearch.com / Demo123456

Author: prajwal3114

.env.example

@@ -0,0 +1,21 @@
+# Backend API Configuration
+DATABASE_URL=postgresql+asyncpg://postgres:password@localhost:5432/qrs
+REDIS_URL=redis://localhost:6379/0
+
+# Security
+SECRET_KEY=your-secret-key-change-this-in-production
+ALGORITHM=HS256
+ACCESS_TOKEN_EXPIRE_MINUTES=30
+
+# CORS
+CORS_ORIGINS=http://localhost:5173,http://localhost:3000,http://localhost:8080
+
+# Finnhub API (optional - will use mock data if not provided)
+FINNHUB_API_KEY=
+
+# Output directory for backtest results
+OUTPUT_DIR=./output
+
+# Server
+HOST=0.0.0.0
+PORT=8000