Promotion of the current `develop` integration state to `main`.

## Contents

| Area | Change |
| --- | --- |
| Analyzer conformance | #418 -- removed the repo-wide
`dotnet_analyzer_diagnostic` relaxation, fixed the 29 `xUnit1051` sites
it hid |
| Docs | #419 -- Codecov coverage shield in the README build status
block |
| Repo config | #417 -- repo-config carry refresh and self-audit carry |

## Conformance issues resolved

Closes #380
Closes #387

#380 (xUnit v3 + AwesomeAssertions, `ILoggerFactory` seam) was already
satisfied in the tree -- verified rather than assumed: 0 `Assert.*`
remaining against 245 `.Should()` calls, `xunit.v3` 3.2.2 pinned with no
v2 package, zero Serilog references in the library, and
`Utilities/LogOptions.cs` matching the LanguageTags reference seam.

#387's four findings were likewise already addressed except finding 1
(analyzer suppression hygiene), which #418 closes. Every remaining
suppression was independently probed by removing it and rebuilding, and
all proved load-bearing (`CA1711`, `CA1707`, `CA1515`, `NoWarn IL3058`).

## Release impact: no auto-publish

This promotion carries **no shipped input**. Per
[WORKFLOW.md](../blob/main/WORKFLOW.md) the inclusion list is
`Utilities/**`, `version.json`, `Directory.Build.props`,
`Directory.Packages.props`; this diff is confined to tests, docs, CI,
and repo config:

```
.editorconfig  .github/workflows/merge-bot-pull-request.yml  AUDIT.md  README.md
UtilitiesTests/*.cs  repo-config/*  spec/secrets.json
```

`Utilities/**` is byte-identical between `main` and `develop`, so the
published package is already current and merging this will correctly
**not** trigger a stable release.

Updated [ptr727.Utilities](https://github.com/ptr727/Utilities) from
4.0.18 to 4.0.28.

<details>
<summary>Release notes</summary>

_Sourced from [ptr727.Utilities's
releases](https://github.com/ptr727/Utilities/releases)._

## 4.0.28

## What's Changed
* Bump the nuget-deps group with 3 updates by @​dependabot[bot] in
ptr727/Utilities#411
* Document the README + HISTORY cspell CI scope in CODESTYLE by @​ptr727
in ptr727/Utilities#413
* Document the README + HISTORY cspell CI scope (main-only) by @​ptr727
in ptr727/Utilities#414
* Bump actions/setup-dotnet from 5.4.0 to 6.0.0 in the actions-deps
group by @​dependabot[bot] in
ptr727/Utilities#415
* Bump actions/setup-dotnet from 5.4.0 to 6.0.0 in the actions-deps
group by @​dependabot[bot] in
ptr727/Utilities#416
* Refresh repo-config carry to current reference; add self-audit carry
by @​ptr727 in ptr727/Utilities#417
* Remove repo-wide analyzer relaxation and honor test cancellation by
@​ptr727 in ptr727/Utilities#418
* Add Codecov coverage shield to the README build status by @​ptr727 in
ptr727/Utilities#419
* Promote develop to main by @​ptr727 in
ptr727/Utilities#420
* Correct WORKFLOW.md audit flow and NUGET_USERNAME secret store by
@​ptr727 in ptr727/Utilities#422
* Describe the 5D audit as reporting defects, not failing by @​ptr727 in
ptr727/Utilities#424
* Promote develop to main by @​ptr727 in
ptr727/Utilities#423
* Spell out the up-to-date ruleset setting in the 5D audit summary by
@​ptr727 in ptr727/Utilities#425
* Promote develop to main by @​ptr727 in
ptr727/Utilities#426
* Bump DavidAnson/markdownlint-cli2-action from 24.0.0 to 24.1.0 in the
actions-deps group by @​dependabot[bot] in
ptr727/Utilities#429
* Bump the nuget-deps group with 1 update by @​dependabot[bot] in
ptr727/Utilities#431


**Full Changelog**:
ptr727/Utilities@4.0.18...4.0.28

Commits viewable in [compare
view](ptr727/Utilities@4.0.18...4.0.28).
</details>

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