Publishing a manifest with a stale version currently produces a
duplicate-version error without identifying the version that was
submitted. This made a request containing `0.4.5` look like a rejected
publication of `0.4.6` in #1615.
Include the submitted `name@version` in the CLI output before sending
the request and in the API duplicate-version error. HTTP 400, the
response structure, and duplicate-rejection behavior remain unchanged.
The service wraps the existing error sentinel so `errors.Is` continues
to work.
Adds a CLI regression test for a failed publication and updates the API
duplicate-error assertion.
Validation:
- Publish command tests passed (`go test ./cmd/publisher/commands -run
TestPublishCommand -count=1`).
- `git diff --check` passed.
- API endpoint tests were attempted but could not run because PostgreSQL
was unavailable on localhost:5432; Docker was also unavailable locally.
Related to #1615.
068a97a2f8