Change the commit menu's key for pasting a commit message to V

We are about to add an entry for copying the commit message to the
clipboard. Its obvious key `c` is already taken by "Add co-author", so
use `C` for copying and `V` for pasting. This matches the keys for
copying and pasting commits in the commits panel.

This means changing the key of an existing entry. We change the one for
pasting and not the one for adding a co-author, because users are
likely to paste a commit message less often than they add a co-author.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

pkg/gui/controllers/helpers/commits_helper.go

@@ -247,7 +247,7 @@ func (self *CommitsHelper) OpenCommitMenu(suggestionFunc func(string) []*types.S
 			OnPress: func() error {
 				return self.pasteCommitMessageFromClipboard()
 			},
-			Keys: menuKey('p'),
+			Keys: menuKey('V'),
 		},
 	}
 	return self.c.Menu(types.CreateMenuOptions{