ci: add the dino art to the release message

[JonasJesus42]

Adds the dino art to the release message.

How it gets there

Discord fetches embed images itself, so it needs a public URL, not an upload. The repo is public, so the file is served from it via raw.githubusercontent.com, pointed at main.

Two consequences worth knowing:

• Replacing the file at the same path replaces the art everywhere, including old messages.
• Discord caches per URL, so a swap won't show up promptly unless it also gets a new filename.

Size

The source was 1254×1254, 2.1 MB. That's a lot to re-fetch on every release, and Discord renders embed images around 400px wide anyway — so it ships resized to 600px and encoded as JPEG: 135 KB, ~16× smaller. Checked the result visually first; the thought bubble, the hoodie and the sign text all stay legible at that size. JPEG over PNG because the illustration is photographic-ish and needs no transparency (562 KB as PNG at the same dimensions).

Verified

• publish.yml parses, 11 steps, last is Notify Discord
• payload is valid JSON with image.url and both fields intact
• the raw URL resolves only once this lands on main — which happens before the publish job runs, so the first message already has it

Note: it's a full-width image. Publishes fire on every merge to main, so this shows up often — switching to thumbnail (small, top-right) is a one-word change if it turns out too loud in the channel.

🤖 Generated with Claude Code

---

Summary by cubic

Release notifications previously contained no artwork; they now include the dino image as a full-width Discord embed image. The workflow uses a public URL on main, so replacing the asset at the same path changes the artwork for existing messages and Discord may cache updates.

New Features

• Adds a 600×600 JPEG optimized to 135 KB for Discord’s typical display size.
• Includes the image URL in the existing publish payload without changing message delivery.

^{Written for commit 93db7c9. Summary will update on new commits.}