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

.env.example

@@ -49,12 +49,51 @@ RSA_PRIVATE_KEY=-----BEGIN RSA PRIVATE KEY-----\nYOUR_KEY_HERE\n-----END RSA PRI
 TRANSPORT_ENCRYPTION=false
 
 # ===========================================
-# Optional: External Services
+# Telegram AI Assistant (NEW - moltbot-nofx)
 # ===========================================
 
-# Telegram notifications (optional)
-# TELEGRAM_BOT_TOKEN=your-bot-token
-# TELEGRAM_CHAT_ID=your-chat-id
+# Telegram Bot Token (get from @BotFather)
+# This enables the AI trading assistant via Telegram
+TELEGRAM_BOT_TOKEN=
+
+# Allowed users (comma-separated Telegram user IDs)
+# Leave empty to allow all users (not recommended for production)
+# Get your ID from @userinfobot
+TELEGRAM_ALLOWED_USERS=
+
+# Admin users (comma-separated Telegram user IDs)
+# Admins can manage bot settings
+TELEGRAM_ADMIN_USERS=
+
+# Rate limit (messages per minute per user)
+TELEGRAM_RATE_LIMIT=30
+
+# Default language: "en" or "zh"
+TELEGRAM_LANGUAGE=zh
+
+# ===========================================
+# AI Model Configuration (for Assistant)
+# ===========================================
+
+# DeepSeek (recommended - cost-effective)
+DEEPSEEK_API_KEY=
+DEEPSEEK_API_URL=
+DEEPSEEK_MODEL=deepseek-chat
+
+# Claude (optional alternative)
+CLAUDE_API_KEY=
+CLAUDE_API_URL=
+CLAUDE_MODEL=
+
+# OpenAI (optional alternative)
+OPENAI_API_KEY=
+OPENAI_API_URL=
+OPENAI_MODEL=
+
+# Qwen (optional alternative)
+QWEN_API_KEY=
+QWEN_API_URL=
+QWEN_MODEL=
 
 DB_TYPE=postgres
 DB_HOST=10.