Initial implementation of xtrm-agent multi-agent system

Multi-agent AI automation system with shared message bus, specialized
roles (coder/researcher/reviewer), and deny-by-default security.

- Config system with Pydantic validation and YAML loading
- Async message bus with inter-agent delegation
- LLM providers: Anthropic (Claude) and LiteLLM (DeepSeek/Kimi/MiniMax)
- Tool system: registry, builtins (file/bash/web), approval engine, MCP client
- Agent engine with tool-calling loop and orchestrator for multi-agent management
- CLI channel (REPL) and Discord channel
- Docker + Dockge deployment config
- Typer CLI: chat, serve, status, agents commands

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

.gitignore

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+__pycache__/
+*.py[cod]
+*$py.class
+*.egg-info/
+dist/
+build/
+.eggs/
+*.egg
+.venv/
+venv/
+.env
+*.log
+.mypy_cache/
+.ruff_cache/
+.pytest_cache/
+data/
+playground.html