Local terminal lifecycle

On supported POSIX desktops, local terminal creation uses tmux or a direct PTY fallback. Both paths respect the process-execution disable setting. A tmux failure does not bypass that setting.

Local backend PTY commands keep their timeout and output limits when a shell exits before its child processes close the terminal. Interactive terminal sessions remain open until closed; they do not acquire a per-command timeout.

The native 3D terminal and Web dashboard share terminal creation behavior. TUI commands using the local execution backend share bounded command behavior. Other platform capability restrictions and approval requirements are unchanged.