feat: NOFXi Agent integrated into NOFX core

This is the key architectural change: NOFXi is no longer a separate
sub-project in nofxi/, but a first-class module in agent/ that sits
on top of NOFX's existing engine.

agent/ package:
- agent.go: Core orchestrator, directly uses NOFX's TraderManager,
  Store, and Market packages. No wrapper/bridge needed.
- brain.go: Proactive intelligence (news scan, market briefs, signal handling)
- sentinel.go: Market anomaly detection (price breakout, volume spike, funding rate)
- scheduler.go: Daily reports, position risk checks
- router.go: Intent routing for natural language (中/英 bilingual)
- i18n.go: Full Chinese/English message catalog
- web.go: Agent REST API on :8900 (chat, klines, ticker)

main.go changes:
- Banner: NOFX → NOFXi
- Agent auto-starts with NOFX (sentinel + brain + scheduler + web)
- Zero breaking changes to existing NOFX functionality

Key difference from old nofxi/:
- Agent reads LIVE data from TraderManager (positions, balances, status)
- Uses market.Get() for full technical indicators (EMA/MACD/RSI/BB)
- No duplicate code — kernel, trader, store all used directly
- Old nofxi/ sub-project will be removed once migration is verified

Architecture:
  NOFX (engine) → kernel + trader + market + store + mcp + telegram
  NOFXi (brain) → agent/ package → uses all of the above

main.go

@@ -1,7 +1,9 @@
 package main
 
 import (
+	"log/slog"
 	"nofx/api"
+	nofxiagent "nofx/agent"
 	"nofx/auth"
 	"nofx/config"
 	"nofx/crypto"
@@ -29,7 +31,8 @@ func main() {
 	logger.Init(nil)
 
 	logger.Info("╔════════════════════════════════════════════════════════════╗")
-	logger.Info("║           🚀 NOFX - AI-Powered Trading System              ║")
+	logger.Info("║          🚀 NOFXi - AI Trading Agent                        ║")
+	logger.Info("║          Powered by NOFX Engine                             ║")
 	logger.Info("╚════════════════════════════════════════════════════════════╝")
 
 	// Initialize global configuration (loaded from .env)
@@ -140,6 +143,17 @@ func main() {
 	// Start Telegram bot (if TELEGRAM_BOT_TOKEN is configured)
 	go telegram.Start(cfg, st, telegramReloadCh)
 
+	// Start NOFXi Agent (proactive intelligence layer)
+	nofxiAgent := nofxiagent.New(traderManager, st, nil, slog.Default())
+	nofxiAgent.Start()
+	defer nofxiAgent.Stop()
+
+	// Start NOFXi Agent Web API (port 8900)
+	agentWeb := nofxiagent.NewWebHandler(nofxiAgent, slog.Default())
+	agentWeb.StartStandalone(8900)
+
+	logger.Info("🧠 NOFXi Agent started (sentinel + brain + scheduler + web:8900)")
+
 	// Wait for interrupt signal
 	quit := make(chan os.Signal, 1)
 	signal.Notify(quit, syscall.SIGINT, syscall.SIGTERM)