feat: add opt-in terminal command hints and detection tests

[Wangmerlyn]

Summary

• add optional command-hint metadata to terminal observations (parsed_tool, parsed_argv) and a separate TerminalWithHintsTool that enables it without changing the default terminal
• implement shlex-based detection (rg/ripgrep) while always returning argv when hints are enabled, keeping base terminal behavior untouched
• add unit/integration coverage including pipeline parsing and opt-in/off scenarios

Testing

python -m pytest tests/tools/terminal/test_terminal_command_hint.py tests/tools/terminal/test_terminal_command_hint_integration.py