Filter the keybindings menu as you type

Looking up a keybinding is a search, so the menu that lists them is the
one that most wants this. Its items do have keys, but only as a reminder
of what they do outside the menu, so nothing is lost by not binding them.

The prompt in front of the input field says what '@' does. It only ever
showed up while the user was typing in the search prompt, so it could
afford to be wordy; on a row that is on screen for as long as the menu
is, it can't.

Co-authored-by: Claude Opus 5 (1M context) <noreply@anthropic.com>

pkg/gui/controllers/options_menu_action.go

@@ -64,6 +64,7 @@ func (self *OptionsMenuAction) Call() error {
 		ColumnAlignment:            []utils.Alignment{utils.AlignRight, utils.AlignLeft},
 		AllowFilteringKeybindings:  true,
 		KeepConflictingKeybindings: true,
+		FilterAsYouType:            true,
 	})
 }