Summary by cubic

Adds multi-command execution to the CLI protocol with stateful, cross‑platform scripts and flexible output control. Replaces command_name with a commands array, updates docs, and expands tests.

• New Features

  • Run multiple commands in one subprocess (PowerShell on Windows, Bash on Unix/macOS)
  • Preserve state across steps (cd, env); reference outputs with $CMD_0_OUTPUT, $CMD_1_OUTPUT
  • UTCP_ARG_argname_UTCP_END placeholders; per-step append_to_final_output (defaults to last only)
  • Improved error handling and a 120s default timeout; JSON output auto-parsed when applicable
  • Registration uses the first command for discovery; docs updated with cross‑platform examples and security notes

• Migration

  • Replace command_name with commands: [{"command": "...", "append_to_final_output": true|false}]
  • For single commands: commands: [{"command": ""}]
  • Use UTCP_ARG__UTCP_END for argument substitution inside commands
  • Assume platform-specific syntax (PowerShell vs Bash); only last command’s output is returned by default