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/config.go

@@ -0,0 +1,98 @@
+package agent
+
+import (
+	"fmt"
+	"os"
+
+	"gopkg.in/yaml.v3"
+)
+
+// Config holds the complete NOFXi configuration.
+type Config struct {
+	Agent     AgentConfig     `yaml:"agent"`
+	Telegram  TelegramConfig  `yaml:"telegram"`
+	LLM       LLMConfig       `yaml:"llm"`
+	Database  DatabaseConfig  `yaml:"database"`
+	Exchanges []ExchangeConfig `yaml:"exchanges"`
+}
+
+type AgentConfig struct {
+	Name     string `yaml:"name"`      // Agent display name
+	Language string `yaml:"language"`   // "en" or "zh"
+	LogLevel string `yaml:"log_level"`  // "debug", "info", "warn", "error"
+	WebPort  int    `yaml:"web_port"`   // REST API port (0 = disabled)
+}
+
+type TelegramConfig struct {
+	Token      string  `yaml:"token"`
+	AllowedIDs []int64 `yaml:"allowed_ids"` // Allowed Telegram user IDs (empty = allow all)
+}
+
+type LLMConfig struct {
+	Provider string `yaml:"provider"`  // "openai", "claw402"
+	BaseURL  string `yaml:"base_url"`  // API base URL
+	APIKey   string `yaml:"api_key"`
+	Model    string `yaml:"model"`     // e.g. "gpt-4o", "deepseek-chat"
+}
+
+type DatabaseConfig struct {
+	Path string `yaml:"path"` // SQLite file path
+}
+
+type ExchangeConfig struct {
+	Name      string `yaml:"name"`       // "binance", "okx", "bybit", etc.
+	APIKey    string `yaml:"api_key"`
+	APISecret string `yaml:"api_secret"`
+	Passphrase string `yaml:"passphrase"` // OKX needs this
+	Testnet   bool   `yaml:"testnet"`
+}
+
+// LoadConfig reads config from a YAML file.
+func LoadConfig(path string) (*Config, error) {
+	data, err := os.ReadFile(path)
+	if err != nil {
+		return nil, fmt.Errorf("read config: %w", err)
+	}
+
+	cfg := &Config{
+		Agent: AgentConfig{
+			Name:     "NOFXi",
+			Language: "en",
+			LogLevel: "info",
+		},
+		Database: DatabaseConfig{
+			Path: "nofxi.db",
+		},
+	}
+
+	if err := yaml.Unmarshal(data, cfg); err != nil {
+		return nil, fmt.Errorf("parse config: %w", err)
+	}
+
+	// Override with env vars if set
+	if v := os.Getenv("NOFXI_TELEGRAM_TOKEN"); v != "" {
+		cfg.Telegram.Token = v
+	}
+	if v := os.Getenv("NOFXI_LLM_API_KEY"); v != "" {
+		cfg.LLM.APIKey = v
+	}
+	if v := os.Getenv("NOFXI_LLM_BASE_URL"); v != "" {
+		cfg.LLM.BaseURL = v
+	}
+
+	return cfg, nil
+}
+
+// Validate checks required fields.
+func (c *Config) Validate() error {
+	if c.Telegram.Token == "" {
+		return fmt.Errorf("telegram.token is required")
+	}
+	if c.LLM.APIKey == "" {
+		return fmt.Errorf("llm.api_key is required")
+	}
+	if c.LLM.Model == "" {
+		return fmt.Errorf("llm.model is required")
+	}
+	return nil
+}