`iframe.contentWindow.print()` does not work for a PDF in Chrome. Chrome backs
every PDF — src URL or blob URL — with its internal `pdf_embedder` extension
rather than a real DOM document, so the frame's `contentDocument` is an empty
shell:
<html><head><link rel="stylesheet"
href="chrome-extension://…/pdf_embedder.css"></head>
<body></body></html>
The PDF *paints* — you can see it in the preview — but `print()` runs against
that empty body, so the operator gets a print dialog full of blank pages and
no error to explain why. Read straight out of a live page to confirm.
A new tab gets Chrome's real PDF viewer, whose own print button works. Same
document, no blank pages.
Affects the delivery-note preview, the quote PDF viewer, and the second quote
viewer in the same file. Popup-blocked is now reported explicitly rather than
appearing to do nothing.
Step A — move the 'Add item' button from the top of the items
section to the bottom of the items list.
Step B — match the quote-form.tsx pattern: every item card is
followed by its own ghost + dashed-border 'Add another item'
button, so the operator never has to scroll back to the top
to add the next line. The dashed-border styling keeps it from
being mistaken for a submit/finish affordance.
The data-testid="dn-adhoc-add-item" selector is preserved on
the per-card buttons so any future test selectors continue to
work.
Fixes PINW-18
