d97e5b0f1a
Ctrl-Insert — Copy selection (MC Store, parity with F5). Shift-Delete — Cut selection (MC Cut, parity with F6). Ctrl-N — EditNew: clear buffer after save prompt if dirty. Shift-Tab — Unindent selection by one tab width (MC parity). Editor::unindent_selection() handles tab/space removal. Tests cover each binding's positive and negative paths.