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

agent/brain.go

@@ -0,0 +1,146 @@
+package agent
+
+import (
+	"encoding/json"
+	"fmt"
+	"io"
+	"log/slog"
+	"net/http"
+	"strings"
+	"sync"
+	"time"
+)
+
+// Brain handles proactive intelligence: signals, news, market briefs.
+type Brain struct {
+	agent         *Agent
+	logger        *slog.Logger
+	stopCh        chan struct{}
+	recentSignals sync.Map // debounce
+}
+
+func NewBrain(agent *Agent, logger *slog.Logger) *Brain {
+	return &Brain{agent: agent, logger: logger, stopCh: make(chan struct{})}
+}
+
+func (b *Brain) Stop() { close(b.stopCh) }
+
+func (b *Brain) HandleSignal(sig Signal) {
+	key := fmt.Sprintf("%s:%s", sig.Type, sig.Symbol)
+	if v, ok := b.recentSignals.Load(key); ok {
+		if time.Since(v.(time.Time)) < 10*time.Minute {
+			return
+		}
+	}
+	b.recentSignals.Store(key, time.Now())
+
+	emoji := map[string]string{"info": "ℹ️", "warning": "⚠️", "critical": "🚨"}
+	e := emoji[sig.Severity]
+	if e == "" { e = "📊" }
+
+	b.agent.notifyAll(fmt.Sprintf("%s *%s*\n\n%s", e, sig.Title, sig.Detail))
+}
+
+func (b *Brain) StartNewsScan(interval time.Duration) {
+	seen := make(map[string]bool)
+	go func() {
+		ticker := time.NewTicker(interval)
+		defer ticker.Stop()
+		for {
+			select {
+			case <-b.stopCh: return
+			case <-ticker.C:
+				b.scanNews(seen)
+			}
+		}
+	}()
+}
+
+func (b *Brain) scanNews(seen map[string]bool) {
+	resp, err := http.Get("https://min-api.cryptocompare.com/data/v2/news/?lang=EN&sortOrder=latest")
+	if err != nil { return }
+	defer resp.Body.Close()
+	body, _ := io.ReadAll(resp.Body)
+
+	var result struct {
+		Data []struct {
+			Title       string `json:"title"`
+			Source      string `json:"source"`
+			URL         string `json:"url"`
+			Body        string `json:"body"`
+			Categories  string `json:"categories"`
+			PublishedOn int64  `json:"published_on"`
+		} `json:"Data"`
+	}
+	json.Unmarshal(body, &result)
+
+	bullish := []string{"surge", "rally", "bullish", "breakout", "ath", "pump", "adoption"}
+	bearish := []string{"crash", "dump", "bearish", "sell-off", "plunge", "hack", "ban", "fraud"}
+
+	for _, d := range result.Data {
+		if seen[d.URL] { continue }
+		seen[d.URL] = true
+		if time.Since(time.Unix(d.PublishedOn, 0)) > 10*time.Minute { continue }
+
+		lower := strings.ToLower(d.Title + " " + d.Body)
+		bc, brc := 0, 0
+		for _, w := range bullish { if strings.Contains(lower, w) { bc++ } }
+		for _, w := range bearish { if strings.Contains(lower, w) { brc++ } }
+
+		if bc == 0 && brc == 0 { continue }
+
+		emoji := "📰"
+		sentiment := "NEUTRAL"
+		if bc > brc { emoji = "🟢"; sentiment = "BULLISH" }
+		if brc > bc { emoji = "🔴"; sentiment = "BEARISH" }
+
+		b.agent.notifyAll(fmt.Sprintf("%s *News*\n\n%s\n\n• Source: %s\n• Sentiment: %s",
+			emoji, d.Title, d.Source, sentiment))
+	}
+
+	if len(seen) > 1000 { for k := range seen { delete(seen, k) } }
+}
+
+func (b *Brain) StartMarketBriefs(hours []int) {
+	go func() {
+		ticker := time.NewTicker(1 * time.Minute)
+		defer ticker.Stop()
+		sent := make(map[string]bool)
+		for {
+			select {
+			case <-b.stopCh: return
+			case now := <-ticker.C:
+				key := now.Format("2006-01-02-15")
+				for _, h := range hours {
+					if now.Hour() == h && now.Minute() == 30 && !sent[key] {
+						sent[key] = true
+						b.sendBrief(h)
+					}
+				}
+			}
+		}
+	}()
+}
+
+func (b *Brain) sendBrief(hour int) {
+	title := "☀️ *早间市场简报*"
+	if hour >= 18 { title = "🌙 *晚间市场简报*" }
+
+	// Fetch BTC/ETH prices for the brief
+	var btcPrice, ethPrice, btcChg, ethChg string
+	for _, sym := range []string{"BTCUSDT", "ETHUSDT"} {
+		resp, err := http.Get(fmt.Sprintf("https://fapi.binance.com/fapi/v1/ticker/24hr?symbol=%s", sym))
+		if err != nil { continue }
+		body, _ := io.ReadAll(resp.Body)
+		resp.Body.Close()
+		var t map[string]string
+		json.Unmarshal(body, &t)
+		if sym == "BTCUSDT" { btcPrice = t["lastPrice"]; btcChg = t["priceChangePercent"] }
+		if sym == "ETHUSDT" { ethPrice = t["lastPrice"]; ethChg = t["priceChangePercent"] }
+	}
+
+	brief := fmt.Sprintf("%s\n\n• BTC: $%s (%s%%)\n• ETH: $%s (%s%%)\n\n_%s_",
+		title, btcPrice, btcChg, ethPrice, ethChg, time.Now().Format("2006-01-02 15:04"))
+
+	b.agent.notifyAll(brief)
+}