refactor: remove all backtest module code and references

Delete backtest/ engine (19 files), api/backtest.go, store/backtest.go,
web backtest components (7 files), API client, types, docs, screenshot.
Clean all backtest references from main.go, api/server.go, store/store.go,
App.tsx, HeaderBar.tsx, LandingPage.tsx, translations, README and docs.

main.go

@@ -3,13 +3,11 @@ package main
 import (
 	"nofx/api"
 	"nofx/auth"
-	"nofx/backtest"
 	"nofx/config"
 	"nofx/crypto"
 	"nofx/telemetry"
 	"nofx/logger"
 	"nofx/manager"
-	"nofx/mcp"
 	_ "nofx/mcp/payment"
 	_ "nofx/mcp/provider"
 	"nofx/store"
@@ -81,7 +79,6 @@ func main() {
 		logger.Fatalf("❌ Failed to initialize database: %v", err)
 	}
 	defer st.Close()
-	backtest.UseDatabaseWithType(st.DB(), st.DBType() == store.DBTypePostgres)
 
 	// Initialize installation ID for experience improvement (anonymous statistics)
 	initInstallationID(st)
@@ -98,13 +95,8 @@ func main() {
 	// time.Sleep(500 * time.Millisecond)
 	logger.Info("📊 Using CoinAnk API for all market data (WebSocket cache disabled)")
 
-	// Create TraderManager and BacktestManager
+	// Create TraderManager
 	traderManager := manager.NewTraderManager()
-	mcpClient := newSharedMCPClient()
-	backtestManager := backtest.NewManager(mcpClient)
-	if err := backtestManager.RestoreRuns(); err != nil {
-		logger.Warnf("⚠️ Failed to restore backtest history: %v", err)
-	}
 
 	// Load all traders from database to memory (may auto-start traders with IsRunning=true)
 	if err := traderManager.LoadTradersFromStore(st); err != nil {
@@ -132,7 +124,7 @@ func main() {
 	}
 
 	// Start API server
-	server := api.NewServer(traderManager, st, cryptoService, backtestManager, cfg.APIServerPort)
+	server := api.NewServer(traderManager, st, cryptoService, cfg.APIServerPort)
 
 	// Create hot-reload channel for Telegram bot; wire it to the API server
 	// so that POST /api/telegram can trigger a bot restart when the token changes.
@@ -163,16 +155,6 @@ func main() {
 	logger.Info("✅ System shut down safely")
 }
 
-// newSharedMCPClient creates a shared MCP AI client (for backtesting)
-func newSharedMCPClient() mcp.AIClient {
-	apiKey := os.Getenv("DEEPSEEK_API_KEY")
-	if apiKey == "" {
-		logger.Warn("⚠️ DEEPSEEK_API_KEY not set, AI features will be unavailable")
-		return nil
-	}
-	return mcp.NewAIClientByProvider("deepseek")
-}
-
 // initInstallationID initializes the anonymous installation ID for experience improvement
 // This ID is persisted in database and used for anonymous usage statistics
 func initInstallationID(st *store.Store) {