feat(nofxi): Phase 3 complete - Exchange factory, Web UI, Strategy runner, Docker

Exchange Factory:
- CreateTrader() supports Binance/OKX/Bybit/Bitget/KuCoin/Gate
- Auto-registers traders from config on startup
- Direct import of nofx/trader packages (merged into main module)

Web UI:
- Dark theme chat interface at :8900
- Quick action sidebar (analyze, watch, positions, balance)
- Real-time health check indicator
- Mobile responsive

Strategy Runner:
- /strategy start BTC 1h - AI auto-analyzes on interval
- /strategy stop <id> - stop strategy
- /strategy list - view active strategies
- Notifications pushed to Telegram on signals
- Configurable intervals: 15m/30m/1h/4h

Docker:
- Multi-stage Dockerfile (alpine, ~20MB)
- docker-compose.yml with volume persistence

Bug fixes:
- Fixed panic on empty exchanges config
- Fixed thinking mode response parsing (qwen3 content:null)
- Added request timeout (55s) in Telegram handler
- Better error logging

nofxi/internal/execution/factory.go

@@ -0,0 +1,52 @@
+package execution
+
+import (
+	"fmt"
+	"strings"
+
+	"nofx/trader/binance"
+	"nofx/trader/bitget"
+	"nofx/trader/bybit"
+	"nofx/trader/gate"
+	"nofx/trader/kucoin"
+	"nofx/trader/okx"
+)
+
+// ExchangeConfig holds credentials for creating a trader.
+type ExchangeConfig struct {
+	Name       string
+	APIKey     string
+	APISecret  string
+	Passphrase string
+	Testnet    bool
+}
+
+// CreateTrader creates a NofxTrader for the given exchange.
+func CreateTrader(cfg ExchangeConfig) (NofxTrader, error) {
+	switch strings.ToLower(cfg.Name) {
+	case "binance":
+		return binance.NewFuturesTrader(cfg.APIKey, cfg.APISecret, "nofxi"), nil
+
+	case "okx":
+		return okx.NewOKXTrader(cfg.APIKey, cfg.APISecret, cfg.Passphrase), nil
+
+	case "bybit":
+		return bybit.NewBybitTrader(cfg.APIKey, cfg.APISecret), nil
+
+	case "bitget":
+		return bitget.NewBitgetTrader(cfg.APIKey, cfg.APISecret, cfg.Passphrase), nil
+
+	case "kucoin":
+		return kucoin.NewKuCoinTrader(cfg.APIKey, cfg.APISecret, cfg.Passphrase), nil
+
+	case "gate":
+		return gate.NewGateTrader(cfg.APIKey, cfg.APISecret), nil
+
+	// Hyperliquid needs private key, not API key/secret
+	// case "hyperliquid":
+	//   return hyperliquid.NewHyperliquidTrader(cfg.APIKey, "", cfg.Testnet)
+
+	default:
+		return nil, fmt.Errorf("unsupported exchange: %s", cfg.Name)
+	}
+}