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/perception/perception.go

@@ -0,0 +1,20 @@
+// Package perception implements the Perception Layer.
+//
+// Phase 2 — stubs for now.
+//
+// Planned capabilities:
+// - Real-time market data monitoring
+// - Price anomaly detection
+// - Position tracking and P/L monitoring
+// - News and sentiment analysis
+// - Custom alert triggers
+package perception
+
+// Monitor is the market perception interface.
+type Monitor interface {
+	// WatchSymbol starts monitoring a symbol for price changes.
+	WatchSymbol(symbol string) error
+
+	// Stop stops all monitoring.
+	Stop()
+}