fix: truncate textinput placeholder (#442)

Co-authored-by: Sean Banko <seanbanko@Seans-MacBook-Air.local>

textinput/textinput.go

@@ -714,7 +714,11 @@ func (m Model) placeholderView() string {
 	v += m.Cursor.View()
 
 	// The rest of the placeholder text
-	v += style(string(p[1:]))
+	var spaces []rune
+	for i := 0; i < m.Width-lipgloss.Width(string(p[1:m.Width])); i++ {
+		spaces = append(spaces, ' ')
+	}
+	v += style(string(append(p[1:m.Width], spaces...)))
 
 	return m.PromptStyle.Render(m.Prompt) + v
 }