fix: NOFXi Agent real AI integration + quality improvements

Critical fixes:
1. Agent now uses NOFX's MCP client for AI calls (real models, not placeholder)
   - Gets AI client from first configured trader's MCP config
   - Added AutoTrader.GetMCPClient() export
2. /analyze uses REAL market data (market.Get → EMA/MACD/RSI/BB/OI/funding)
   then sends to AI — no more hallucinated prices
3. AI chat enriches prompts with live market data when user mentions a coin
4. Fallback: if AI unavailable, shows raw formatted market data (still useful)

Router improvements:
- Better natural language detection for Chinese
- '该不该买' '走势' '趋势' '行情' → analyze intent
- '多少钱' '赚了' '亏了' → query intent
- Fewer messages falling through to generic chat

Web UI:
- Endpoints updated to /api/agent/* namespace
- nofxi.html served at agent root (localhost:8900)

Result: AI analysis now shows real BTC price, real RSI, real EMA — not fiction.

trader/auto_trader.go

@@ -588,6 +588,11 @@ func (at *AutoTrader) GetStore() *store.Store {
 	return at.store
 }
 
+// GetMCPClient returns the AI client for NOFXi agent integration.
+func (at *AutoTrader) GetMCPClient() mcp.AIClient {
+	return at.mcpClient
+}
+
 // calculatePnLPercentage calculates P&L percentage (based on margin, automatically considers leverage)
 // Return rate = Unrealized P&L / Margin x 100%
 func calculatePnLPercentage(unrealizedPnl, marginUsed float64) float64 {