feat: remove FullWidth helper (not needed)

group.go

@@ -269,7 +269,7 @@ func (g *Group) Update(msg tea.Msg) (tea.Model, tea.Cmd) {
 	switch msg := msg.(type) {
 	case tea.WindowSizeMsg:
 		g.WithHeight(min(g.fullHeight(), msg.Height-1))
-		g.WithWidth(min(g.fullWidth(), msg.Width-1))
+		g.WithWidth(msg.Width)
 	case nextFieldMsg:
 		cmds = append(cmds, g.nextField()...)
 	case prevFieldMsg:
@@ -291,16 +291,6 @@ func (g *Group) fullHeight() int {
 	return height
 }
 
-// width returns the full width of the group.
-func (g *Group) fullWidth() int {
-	width := g.selector.Total()
-	g.selector.Range(func(_ int, field Field) bool {
-		width += lipgloss.Width(field.View())
-		return true
-	})
-	return width
-}
-
 func (g *Group) getContent() (int, string) {
 	var fields strings.Builder
 	var offset int