fix: source.unsplash.com/random was deprecated in 2024 (now 503s)

[kiluazen]

src/blocks.ts references the deprecated source.unsplash.com/random endpoint, which Unsplash retired in mid-2024 and which now returns HTTP 503 instead of an image.

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Why this is needed

source.unsplash.com/random was deprecated by Unsplash in mid-2024 and the endpoint now returns 503 errors. Browser screenshots typically render a broken image icon instead of the intended placeholder.

You can verify in any browser:

curl -I https://source.unsplash.com/random/800x600?office
# HTTP/1.1 503 Service Unavailable

What this PR changes

Replaces the six broken source.unsplash.com/random/200x14N URLs in the MJML grid example block with picsum.photos seeded URLs of the same dimensions, so the placeholder grid renders again.

Replacement details

Picsum is a maintained random-image CDN (no auth), and a seed/... prefix gives stable but distinct images per cell so the grid example keeps its visual variety. Image dimensions are unchanged.

Background

I'm tracking deprecated image-CDN URLs across public repos as part of tteg, a tiny CLI/HTTP API I built to make it easy to drop real Unsplash photos into projects without registering an Unsplash app or managing API keys. tteg isn't a dependency of this PR — the fix above is dependency-free. But if you ever want to swap the static replacement for something topic-aware, the no-key HTTP API is at https://tteg-api-53227342417.asia-south1.run.app/search?q=<query>&n=1 (CORS-on, no auth).

A 16k-files-across-885-repos summary of the deprecation is at kiluazen/tteg/RESEARCH.md.

[kiluazen]

Quick post-PR addendum (purely informational): I built a public scanner that highlights this same broken-URL pattern in any landing page — useful for verifying the fix lands cleanly, or for finding other places source.unsplash.com/random slipped in.

Pre-loaded scan example: https://tteg.kushalsm.com/scan?url=

Source: https://github.com/kiluazen/tteg-landing/blob/main/scan.html (Cloudflare Pages Function does the fetch so it works for any HTTPS site). Not a dependency of this PR — just a tool you may find handy.