Add copy-on-select option to the Codex Desktop terminal

What feature would you like to see?

Please add an optional copy-on-select setting for the terminal embedded in Codex Desktop.

When enabled, any non-empty mouse selection in the terminal would copy to the clipboard automatically. This would include drag selection and double-click word selection.

This is an intentional workflow supported by many terminal emulators, and some users rely on it. When the embedded terminal does not support the same option, the next paste can unexpectedly paste stale clipboard contents instead of the text that was just selected.