Custom terminal path setting removed from Code CLI launch

What changed

The Code CLI launch dialog no longer accepts a custom terminal executable path. The terminal is now picked from the list of terminals detected on the system (code_cli.get_available_terminals).

Why this matters to the user

Users who pointed the launcher at a terminal binary outside the detected list (e.g. a portable install in a non-standard location) can no longer do so; only detected terminals are selectable. A previously saved custom path is ignored.

What the user should do

Install the preferred terminal in a standard location so detection picks it up, or launch the CLI tool manually from that terminal. If custom paths turn out to be needed, file a feature request.

Notes for release manager

Same PR as the OpenClaw settings-page merge entry; consider grouping under one "Code CLI page rework" section.