Harden terminal output isolation and recovery

What's Changed

• Added per-session Repair display plus the authenticated redraw API and mt_redraw/Mt-Redraw helpers; a serialized PTY row pulse repaints the foreground TUI while browser geometry stays canonical.
• Added mt_run_isolated/Mt-RunIsolated for browsers, profilers, daemons, and watchers with exact argv, closed stdin, separate stdout/stderr artifacts, and nohup lifecycle isolation on macOS/Linux.
• Hardened detached debug launches so delayed native diagnostics cannot inherit and corrupt an agent terminal.