Right-clicking a tab now takes over the browser menu and shows four
close operations scoped to the current pane:
- Close
- Close Other Tabs
- Close Tabs to the Left
- Close Tabs to the Right
Items gray out when nothing is eligible (single tab / strip ends).
Bulk closes reuse the per-tab onClose path, so descriptor onClose
callbacks and terminal pty release still run for every close. Labels
are i18n'd (zh/en).