[Bug]: the Zeabur one-click deploy button 404s, and the documented template update command targets the same dead code

What

The README's Zeabur one-click deploy button renders normally but links to a template that no longer exists. https://zeabur.com/templates/Q82M3Y returns 404.

The same code appears in the maintainer workflow, so this is not only a stale README link:

# deploy/zeabur/README.md:21
npx zeabur@latest template update -c Q82M3Y -f template.yml

One dead code, two symptoms: users clicking the button hit a 404, and the documented command for updating the published template targets something Zeabur no longer serves.

Why it matters

The button looks healthy, because the badge SVG still resolves. A user cannot tell it is dead until after they click. Railway and Sealos both work, so Zeabur is the only broken entry in that table, and the table is the first thing the README offers for deploying without Docker.

It also means deploy/zeabur/template.yml, which is ~930 lines and actively maintained, has no working published target.

Proof

Probed each button in the table, three times each, with a browser User-Agent:

200  https://railway.com/deploy/insforge
404  https://zeabur.com/templates/Q82M3Y      <- 3/3 attempts
200  https://sealos.io/products/app-store/insforge
200  https://repocloud.io/details/InsForge/
200  https://zeabur.com/button.svg            <- badge still renders

Ruled out the obvious false positives rather than filing on one curl:

• https://zeabur.com/ returns 200, so the site is up.
• https://zeabur.com/templates returns 200, so the path prefix is valid.
• https://zeabur.com/templates/ZZZZZZ, a deliberately bogus code, also returns 404. Identical response to Q82M3Y, which is what a missing template looks like rather than an unsupported URL shape.
• The 404 body contains a literal 404, so it is a real not-found page and not a soft redirect.

Root cause

The template code is hardcoded in two places and there is nothing that checks either:

• README.md:261 in the one-click deployment table.
• deploy/zeabur/README.md:21 in the update command.

The link was added in 2225d6359 ("add one-click deployment to README.md"). Whatever happened to the published template since, unpublished, deleted, or recreated under a different code, neither reference was updated, and no CI job probes these URLs.

Proposed fix

I do not know the current code, and guessing one would be worse than leaving it. This needs a maintainer decision between:

1. Republish the template and update both references to the new code.
2. Drop Zeabur from the table and remove or mark deploy/zeabur/ accordingly.

Happy to do either once you say which. If it helps, a small link-check over the README deploy buttons would catch the next one, though I would file that separately rather than bundle it.

Acceptance criteria

• The Zeabur entry in the README either resolves with a 200 or is removed.
• deploy/zeabur/README.md documents a template code that exists, or the file reflects that the template is unpublished.
• No remaining reference to a template code that 404s.

Relation to #1395

#1395 covers the deployment support matrix and stale image pins, and it does touch Zeabur, but specifically deploy/zeabur/template.yml:873 pinning insforge-oss:v2.0.0. It does not mention the template code or the dead link. I filed this separately because it is a different failure, but if you would rather fold it into #1395 I am fine with that, and it is already assigned.