Function handle_delete_tab 

pub(super) fn handle_delete_tab(
    state: &mut State,
    workspace_id: String,
    tab_id: String,
    force: bool,
) -> Vec<Event>

Phase E.2b — delete a tab from a workspace. Idempotent: deleting a missing tab is a silent no-op. If the deleted tab was the active tab, the workspace’s active tab becomes the next tab in tab_ids (or the previous one if the deleted was last; or None if the workspace is now empty), and an Event::ActiveTabChanged is emitted alongside Event::TabDeleted.