[feature request] Make duplicate tabs apparent

For users with lots of tabs, a simple but useful feature would be to highlight duplicate tabs with the same colors when you do T to show and filter the list of open tabs.

A more advanced feature request would be to allow the list of open tabs via T to remain open and select or mark tabs in the search result for deletion. Or, allow open tabs to remain open and then you can select a tab to open, see it in the background, and Ctrl+W to delete the tab.

These features make it possible to clean your tabs easily by searching for undesirable tabs and deleting them without needing to perform a search for every tab (since that tab list is kept open).

Start by tracing the T command that shows and filters the open-tab list; the issue does not name a file or test. Clarify whether duplicate highlighting or persistent tab selection is the intended scope, then verify that the chosen behavior supports finding and deleting tabs without repeating searches, including the Ctrl+W flow.