- Add config_paths.py for XDG-compliant path resolution
- Update all servers to use user-writable locations (logs, tokens, .env)
- Make .env file optional - server works with environment variables only
- Default paths: ~/.local/share for data, ~/.local/state for logs
- Update Nix wrapper with XDG defaults and helpful postInstall message
- Update README.md with environment variable configuration documentation
Fixes OSError when running in Nix store (read-only filesystem)
