Phase 1: SQLite persistence layer

- Add modernc.org/sqlite (pure Go, no CGO)
- db/ package: trades, orders, config_log tables + CRUD
- Trade persistence: every closed trade saved to SQLite
- Restart recovery: open positions restored from DB
- Automatic migration on startup

main.go

@@ -11,6 +11,7 @@ import (
 	"syscall"
 	"time"
 
+	"exchange-monitor/db"
 	"exchange-monitor/exchange"
 )
 
@@ -34,8 +35,16 @@ func main() {
 	store := NewPriceStore()
 	notifier := NewNotifier(cfg.TelegramBotToken, cfg.TelegramChatID)
 
+	// Initialize SQLite database
+	database, err := db.Open("")
+	if err != nil {
+		log.Printf("[DB] Failed to open database: %v", err)
+	} else {
+		defer database.Close()
+	}
+
 	// Initialize trader
-	trader := NewTrader(cfg)
+	trader := NewTrader(cfg, database)
 	if trader.IsConfigured() {
 		modeLabel := trader.ModeLabel()
 		log.Printf("[Trader] %s mode: automated trading ENABLED (threshold >= %.2f%%, $%.0f/trade)",