feat: redesign backtest module UI and fix 404 issue

- Fix backtest API 404 by registering routes in setupRoutes()
- Redesign BacktestPage with 3-step wizard configuration
- Add progress ring visualization with animation
- Add equity chart with trade markers using Recharts
- Add trade timeline with card-style display
- Add stats cards for equity, return, drawdown, sharpe
- Add tab navigation for overview/chart/trades/decisions
- Improve run history list with status icons
- Add lightweight-charts dependency (for future use)

api/server.go

@@ -187,6 +187,10 @@ func (s *Server) setupRoutes() {
 			protected.GET("/decisions", s.handleDecisions)
 			protected.GET("/decisions/latest", s.handleLatestDecisions)
 			protected.GET("/statistics", s.handleStatistics)
+
+			// Backtest routes
+			backtest := protected.Group("/backtest")
+			s.registerBacktestRoutes(backtest)
 		}
 	}
 }