Add Copy & Delete to the context menu

Copies the item (or the selection, as plain lines) and removes it in one
step — the 'take this out' gesture. No shortcut: Cmd+X belongs to the text
fields, and a panel binding would steal it.

AGENTS.md

@@ -60,7 +60,7 @@ clicking an item copies it back to the clipboard.
   switches sections. Click = select (Shift+click for a range); the selection
   bar offers Copy (single item), Copy as List, Copy as Lines and Delete;
   right-click = context menu acting on the whole selection (Copy, Copy as List,
-  Copy as Lines, Done, Edit, Open, Merge, Move To, Delete). Esc clears the
+  Copy as Lines, Copy & Delete, Done, Edit, Open, Merge, Move To, Delete). Esc clears the
   selection before it hides the panel. Selection is scoped to the current view:
   switching workspace, switching tab, or closing search clears it. Drop target for images/files.
 - `Sources/Prompt/PanelController.swift` — owns the floating `NSPanel`