Revert the Docker Hub short description mechanism

[ptr727]

Reverts #32 (90504d38e274dad1dd1894dee7fe47d1881ae91f).

Nothing is wrong with the implementation. It is the wrong place for it.

Setting the Docker Hub short description from the README intro affects every docker project in the fleet, and the hub already owns the audit half of it: spec/audit.py flags a short description that has drifted from the README intro, on any repo. Adding the push half in one repo leaves that repo diverged from every other docker project and pre-empts a decision that is not this repo's to make.

The hub is working out a deterministic approach. This returns the repo to the audit-only state so it matches the fleet while that happens, and so a later develop -> main promotion cannot carry the mechanism silently.

Why it merged in the first place

The maintainer authorized merging six conformance PRs. #32 was opened afterwards, as the mechanism behind a Docker Hub description change that had been authorized separately, and I extended that merge authorization to it rather than asking. That was mine to ask, not to assume.

Practically the exposure was nil: both added steps are gated inputs.push && inputs.branch == 'main', #32 landed on develop only, and no promotion or publish has run since, so nothing was ever pushed to Docker Hub.

What is preserved

The implementation and its ten test cases are on #32 and in this branch's history, so the hub can lift it as-is if it wants the push half. The guards it accumulated over three review rounds are the part worth keeping:

• markdown structure after the H1 (headings, lists, quotes, tables, fences, HTML, badges, tilde fences, ordered lists)
• inline and reference links
• the 100-character Docker Hub cap
• CRLF handling and leading-whitespace trimming, since CommonMark allows 3 leading spaces before a heading

Verification

• git diff 95af4d7 HEAD is empty: build-docker-task.yml is byte-identical to its state before Set the Docker Hub short description from the README intro #32.
• Zero references to short-description remain in the workflow.
• actionlint exits 0; editorconfig-checker exits 0.

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 44.96%. Comparing base (90504d3) to head (379d1ff).

Additional details and impacted files

@@           Coverage Diff            @@
##           develop      #33   +/-   ##
========================================
  Coverage    44.96%   44.96%           
========================================
  Files           25       25           
  Lines         3398     3398           
  Branches       259      259           
========================================
  Hits          1528     1528           
  Misses        1824     1824           
  Partials        46       46           

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[Copilot]

Pull request overview

This PR reverts the Docker Hub short-description update mechanism that was previously added to the Docker build/publish workflow, returning the repository to an audit-only state that matches the rest of the fleet’s docker projects.

Changes:

• Removed the workflow step that parsed README.md to derive a Docker Hub short description.
• Removed the short-description: input wiring into the Docker Hub description update action.