Add MCP tools integration for Discord bot

Major improvements to LiteLLM Discord bot with MCP (Model Context Protocol) tools support:

Features added:
- MCP tools discovery and integration with LiteLLM proxy
- Fetch and convert 40+ GitHub MCP tools to OpenAI format
- Tool calling flow with placeholder execution (pending MCP endpoint confirmation)
- Dynamic tool injection based on LiteLLM MCP server configuration
- Enhanced system prompt with tool usage guidance
- Added ENABLE_TOOLS environment variable for easy toggle
- Comprehensive debug logging for troubleshooting

Technical changes:
- Added httpx>=0.25.0 dependency for async MCP API calls
- Implemented get_available_mcp_tools() to query /v1/mcp/server and /v1/mcp/tools endpoints
- Convert MCP tool schemas to OpenAI function calling format
- Detect and handle tool_calls in model responses
- Added system_prompt.txt for customizable bot behavior
- Updated README with better documentation and setup instructions
- Created claude.md with detailed development notes and upgrade roadmap

Configuration:
- New ENABLE_TOOLS flag in .env to control MCP integration
- DEBUG_LOGGING for detailed execution logs
- System prompt file support for easy customization

Known limitations:
- Tool execution currently uses placeholders (MCP execution endpoint needs verification)
- Limited to 50 tools to avoid overwhelming the model
- Requires LiteLLM proxy with MCP server configured

Next steps:
- Verify correct LiteLLM MCP tool execution endpoint
- Implement actual tool execution via MCP proxy
- Test end-to-end GitHub operations through Discord

🤖 Generated with [Claude Code](https://claude.com/claude-code)

Co-Authored-By: Claude <noreply@anthropic.com>

v2/.env.example

@@ -1,4 +1,24 @@
+# Discord Bot Token - Get from https://discord.com/developers/applications
 DISCORD_TOKEN=your_discord_bot_token
-OPENAI_API_KEY=your_openai_api_key
-OPENWEBUI_API_BASE=http://your.api.endpoint/v1
-MODEL_NAME="Your_Model_Name"
+
+# LiteLLM API Configuration
+LITELLM_API_KEY=sk-1234
+LITELLM_API_BASE=http://localhost:4000
+
+# Model name (any model supported by your LiteLLM proxy)
+MODEL_NAME=gpt-4-turbo-preview
+
+# System Prompt Configuration (optional)
+SYSTEM_PROMPT_FILE=./system_prompt.txt
+
+# Maximum tokens to use for conversation history (optional, default: 3000)
+MAX_HISTORY_TOKENS=3000
+
+# Enable debug logging (optional, default: false)
+# Set to 'true' to see detailed logs for troubleshooting
+DEBUG_LOGGING=false
+
+# Enable MCP tools integration (optional, default: false)
+# Set to 'true' to allow the bot to use tools configured in your LiteLLM proxy
+# Tools are auto-executed without user confirmation
+ENABLE_TOOLS=false