site: add a print stylesheet so an entry page prints as a clean licence record #105

Why it matters
An entry page (licence, commercial stance, credit line, dated evidence quotes) is exactly what a developer prints or saves to PDF for a project's licence folder. Today printing includes the sticky nav, the filter bar on the home page, the back-to-top button, the Sponsors iframes and, on a dark-mode OS, inverted colours with the source URLs invisible.

Evidence

• grep -c '@media print' site/public/styles.css → 0.

Suggested approach
One @media print block: hide .topbar nav, .controls, .to-top, iframe, .page-actions button, .skip-link; force the light tokens; print a[href^="http"]::after { content: " (" attr(href) ")" } for source links; break-inside: avoid on the evidence block.

Done when
Print preview of an entry page shows title, licence table, credit line, Notes, Evidence with dates, and source URLs in black on white, nothing else.