Website Builder appointment product form reorganized with new booking window control

The appointment product form has been cleaned up for better clarity. The 'Duration & Location' section no longer contains buffer time and minimum notice time settings—these have moved into a dedicated 'Buffers and Notice times' section. A new 'Book within the next' setting lets you set a maximum notice time, controlling how far ahead customers can book. Both 'Buffers and Notice times' and 'Advanced elements' sections now collapse by default since they contain only optional settings, keeping the form focused with details available when you need them.