Add screenshots to each item — the catalog landing pages render them the day they exist

[justinmerrell]

Every one of the 13 items in this repository ships media/icon.png and nothing
else. No item has media/screenshots/.

The platform side is already built and waiting: listing.yaml accepts
spec.screenshots as [{ file, caption }], the importer resolves each to a
Files.File, and CatalogListingResponse.screenshots[] comes back with
url / thumbnailUrl / largeUrl / width / height / caption /
sortIndex already ordered. The console renders them in
CatalogScreenshotGallery.svelte, and the new public landing pages at
musher.dev/catalog/{slug} render them the day they exist — no code change on
either side.

Those landing pages are paid-ad destinations for people who have never seen the
app. Without a screenshot the page leads with a spec card (services, setup
values, compute, storage) — which is honest, checkable product truth, and is the
right hero for a technical buyer — but it cannot show someone what n8n's canvas
or Open WebUI's chat actually looks like. For a cold click that is the single
biggest lift available.

Suggested shape: two or three screenshots per item, captioned, showing the
first screen a person sees after deploying rather than a feature tour. Priority
order by traffic intent: n8n, open-webui, langflow, flowise, litellm,
code-server, label-studio, mlflow, meilisearch, qdrant, openclaw.