feat: Add Telegram AI Assistant (moltbot-nofx integration)

- Add assistant package with AI Agent runtime
  - agent.go: Core agent loop with tool calling
  - session.go: Conversation memory management
  - tool.go: Tool interface and base implementation
  - trading_tools.go: Trading-specific tools (13 tools)
  - prompts.go: Trading expert system prompts (EN/ZH)

- Add telegram package for Telegram bot integration
  - bot.go: Telegram bot with rate limiting & access control
  - config.go: Environment-based configuration

- Update main.go to initialize Telegram bot on startup
- Update .env.example with new configuration options
- Add gopkg.in/telebot.v3 dependency

Trading tools available:
- Query: get_balance, get_positions, list_traders, get_trader_status
- Control: start_trader, stop_trader
- Trading: get_market_price, open_long, open_short, close_position
- Config: list_strategies, list_exchanges, list_ai_models

telegram/config.go

@@ -0,0 +1,60 @@
+package telegram
+
+import (
+	"os"
+	"strconv"
+	"strings"
+)
+
+// LoadConfigFromEnv loads Telegram bot configuration from environment variables
+func LoadConfigFromEnv() BotConfig {
+	config := DefaultBotConfig()
+
+	// Bot token (required)
+	config.Token = os.Getenv("TELEGRAM_BOT_TOKEN")
+
+	// Webhook settings
+	if webhook := os.Getenv("TELEGRAM_WEBHOOK_URL"); webhook != "" {
+		config.UseWebhook = true
+		config.WebhookURL = webhook
+	}
+	if port := os.Getenv("TELEGRAM_WEBHOOK_PORT"); port != "" {
+		if p, err := strconv.Atoi(port); err == nil {
+			config.WebhookPort = p
+		}
+	}
+
+	// Allowed users (comma-separated list of user IDs)
+	if allowedStr := os.Getenv("TELEGRAM_ALLOWED_USERS"); allowedStr != "" {
+		for _, idStr := range strings.Split(allowedStr, ",") {
+			idStr = strings.TrimSpace(idStr)
+			if id, err := strconv.ParseInt(idStr, 10, 64); err == nil {
+				config.AllowedUserIDs = append(config.AllowedUserIDs, id)
+			}
+		}
+	}
+
+	// Admin users
+	if adminStr := os.Getenv("TELEGRAM_ADMIN_USERS"); adminStr != "" {
+		for _, idStr := range strings.Split(adminStr, ",") {
+			idStr = strings.TrimSpace(idStr)
+			if id, err := strconv.ParseInt(idStr, 10, 64); err == nil {
+				config.AdminUserIDs = append(config.AdminUserIDs, id)
+			}
+		}
+	}
+
+	// Rate limiting
+	if rateStr := os.Getenv("TELEGRAM_RATE_LIMIT"); rateStr != "" {
+		if rate, err := strconv.Atoi(rateStr); err == nil {
+			config.MaxMessagesPerMinute = rate
+		}
+	}
+
+	// Language
+	if lang := os.Getenv("TELEGRAM_LANGUAGE"); lang != "" {
+		config.DefaultLanguage = lang
+	}
+
+	return config
+}