Align ci.yml with the canonical template exactly

[StuartMeeks]

What changed

Removes the release job. ci.yml's non-comment content is now identical to templates/.github/workflows/ci.yml apart from the tag glob — which makes it identical to SelfUpdate's, verified by diff rather than by eye.

Why

This repo was the estate's only divergence from the canonical workflow, and I only noticed because you pushed back. Auth and SelfUpdate already matched the template — SelfUpdate exactly, Auth with one gnome-keyring step that has an EXCEPTIONS.md entry. That alignment was real and achieved. Settings sat outside it while the audit reported green, because §3.0 checks filenames, §3.1 checks job names, and nothing checked what actually runs.

Two earlier attempts at reconciling this made it worse, and both are reverted:

1. Widening §3.1 to permit any tag-gated job downstream of publish — weakening a clause so a repo passes, which is the one thing the standards repo exists to stop.
2. Folding the release steps into publish — kept the four job names and moved the divergence somewhere no check looked.

The job is simply gone.

Consumer impact

None. The job only ever ran on a v* tag, after the package had already been pushed to nuget.org. Publishing is untouched — same publish job, same trusted-publishing OIDC flow, same artifact.

The behaviour change is operational, not consumer-facing: GitHub releases for this package are now cut by hand, as they already were in all four other repos.

Enforcement

STANDARD.md §3.0.1 (in Standards) now requires this match, and audit-drift.sh has a 3.0.1 workflow content row that checks it.

Verified against both wrong attempts — with the release job, and with the folded steps, 3.0 and 3.1 stay PASS while 3.0.1 goes FAIL:

                        Auth    Auth.Providers  SelfUpdate  Settings  Splash
3.0   workflow file set  PASS       FAIL           PASS       PASS     FAIL
3.0.1 workflow content   PASS       FAIL           PASS       FAIL     FAIL   <-- before this PR
3.1   gate job `ci`      PASS       FAIL           PASS       PASS     FAIL

Checklist

• Build is clean — no code changes
• Tests pass on every shipped target framework — unchanged; CI proves it on this PR
• Public API changes carry XML docs — none
• CHANGELOG.md updated under [Unreleased]
• Dependency floors unchanged

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