Adds "Copy" and "Export to file" buttons to the Terminal IO inspector so
recorded VT events can be saved outside the app for sharing or analysis.
Found myself needing/wishing for this while I was debugging my tmux fork
with libghostty-vt.
Disclaimer: I haven't considered performance at all, so please lmk if
there are anything here you would like me to optimize.
631c71e41c