Create Purchase Order: A Cleaner Supplier Step

The Create Purchase Order drawer used to open with the entire supplier list expanded, pushing the Products and Notes steps below the fold. Now:

• The supplier list starts collapsed to the first five, with a Show more / Show less toggle — the same control the shipments list uses. It resets to five when you start a new search.
• Picking a supplier collapses the Supplier step and opens Products automatically, so the flow reads top-down (Supplier → Products → Notes) and the later steps stay in view without scrolling.
• Products uses the same standard Show more toggle instead of the old full-width "Load more products" button, so the drawer looks consistent step to step.