openApp() passes page options through, so the showcase run sets
deviceScaleFactor 2 — same CSS viewport and layout as the tests, 2800x2000 px
images that stay sharp where the README scales them down.
A shot names a ribbon tab and, optionally, where the caret goes: the tables
one lands in a cell, so the contextual Table Layout tab is up. The floating
table toolbar is hidden while shooting — it covered the table the ribbon is
already showing. `data-tab` on the tab buttons is what the script clicks.
scripts/showcase/run.mjs builds three sample documents plus a review
variant as .odt and .docx through the app's own exporters in headless
Chromium, opens each through the file dialog and takes the README
screenshots; docs/showcase/ holds the results. The README gets a
light/dark hero picture and a gallery of four tiles.