feat: init nofxi - AI Trading Agent module

NOFXi — Your AI Trading Agent, built on NOFX.

Architecture:
- Agent Core: intent routing, conversation memory, trade confirmation
- Memory: SQLite (trades, conversations, preferences, strategies)
- Thinking: LLM client (OpenAI/claw402/DeepSeek compatible)
- Execution: Bridge to NOFX trader engine (9 exchanges)
- Perception: Market monitor, price alerts, anomaly detection
- Interaction: Telegram bot + REST API + OpenAI-compatible endpoint

Features:
- Natural language trading (中英文)
- /buy /sell /analyze /watch /alert /positions /balance
- Daily P/L reports, portfolio risk checks
- Trade confirmation flow (safety first)
- Price polling and alert notifications

nofxi/internal/agent/watchcmd.go

@@ -0,0 +1,125 @@
+package agent
+
+import (
+	"fmt"
+	"strconv"
+	"strings"
+)
+
+// HandleWatchCommand processes /watch and /alert commands.
+// Returns response text. Called from HandleMessage when intent is detected.
+func (a *Agent) HandleWatchCommand(text string) string {
+	lower := strings.ToLower(strings.TrimSpace(text))
+
+	// /watch BTC
+	if strings.HasPrefix(lower, "/watch") {
+		parts := strings.Fields(text)
+		if len(parts) < 2 {
+			return a.listWatched()
+		}
+		symbol := strings.ToUpper(parts[1])
+		if !strings.HasSuffix(symbol, "USDT") {
+			symbol += "USDT"
+		}
+		if a.monitor != nil {
+			a.monitor.Watch(symbol)
+			return fmt.Sprintf("👁️ Now watching *%s*. I'll track the price.", symbol)
+		}
+		return "⚠️ Market monitor not available."
+	}
+
+	// /unwatch BTC
+	if strings.HasPrefix(lower, "/unwatch") {
+		parts := strings.Fields(text)
+		if len(parts) < 2 {
+			return "Usage: `/unwatch BTC`"
+		}
+		symbol := strings.ToUpper(parts[1])
+		if !strings.HasSuffix(symbol, "USDT") {
+			symbol += "USDT"
+		}
+		if a.monitor != nil {
+			a.monitor.Unwatch(symbol)
+			return fmt.Sprintf("🚫 Stopped watching *%s*.", symbol)
+		}
+		return "⚠️ Market monitor not available."
+	}
+
+	// /alert BTC above 100000
+	if strings.HasPrefix(lower, "/alert") {
+		parts := strings.Fields(text)
+		if len(parts) < 4 {
+			return "Usage: `/alert BTC above 100000` or `/alert ETH below 3000`"
+		}
+		symbol := strings.ToUpper(parts[1])
+		if !strings.HasSuffix(symbol, "USDT") {
+			symbol += "USDT"
+		}
+		direction := strings.ToLower(parts[2])
+		if direction != "above" && direction != "below" {
+			return "Direction must be `above` or `below`."
+		}
+		threshold, err := strconv.ParseFloat(parts[3], 64)
+		if err != nil {
+			return fmt.Sprintf("Invalid price: %s", parts[3])
+		}
+
+		if a.monitor != nil {
+			a.monitor.Watch(symbol) // Ensure we're watching it
+			a.monitor.AddAlert(symbol, direction, threshold)
+			emoji := "📈"
+			if direction == "below" {
+				emoji = "📉"
+			}
+			return fmt.Sprintf("%s Alert set: *%s* %s $%.2f\nI'll notify you when it triggers.",
+				emoji, symbol, direction, threshold)
+		}
+		return "⚠️ Market monitor not available."
+	}
+
+	// /price BTC
+	if strings.HasPrefix(lower, "/price") {
+		parts := strings.Fields(text)
+		if len(parts) < 2 {
+			return "Usage: `/price BTC`"
+		}
+		symbol := strings.ToUpper(parts[1])
+		if !strings.HasSuffix(symbol, "USDT") {
+			symbol += "USDT"
+		}
+		if a.monitor != nil {
+			if snap, ok := a.monitor.GetSnapshot(symbol); ok && snap.LastPrice > 0 {
+				return fmt.Sprintf("💰 *%s*: $%.4f\n_Updated: %s_",
+					symbol, snap.LastPrice, snap.UpdatedAt.Format("15:04:05"))
+			}
+			// Not watching yet, watch and return message
+			a.monitor.Watch(symbol)
+			return fmt.Sprintf("👁️ Started watching *%s*. Price will be available in ~30s.", symbol)
+		}
+		return "⚠️ Market monitor not available."
+	}
+
+	return ""
+}
+
+func (a *Agent) listWatched() string {
+	if a.monitor == nil {
+		return "⚠️ Market monitor not available."
+	}
+	snaps := a.monitor.GetAllSnapshots()
+	if len(snaps) == 0 {
+		return "📭 Not watching any symbols. Use `/watch BTC` to start."
+	}
+
+	var sb strings.Builder
+	sb.WriteString("👁️ *Watching*\n\n")
+	for symbol, snap := range snaps {
+		if snap.LastPrice > 0 {
+			sb.WriteString(fmt.Sprintf("• *%s*: $%.4f (%s)\n",
+				symbol, snap.LastPrice, snap.UpdatedAt.Format("15:04:05")))
+		} else {
+			sb.WriteString(fmt.Sprintf("• *%s*: waiting for data...\n", symbol))
+		}
+	}
+	return sb.String()
+}