- Add WhitespaceAuthorization_ValidXApiKey_Returns200: pins the IsNullOrWhiteSpace
fall-through — a present-but-blank Authorization header is treated as absent so a
valid X-API-Key still authenticates (200).
- Remove MissingBearer_Returns401 (added in 510559e): identical path to
NeitherHeader_Returns401 (no Authorization + no X-API-Key → 401); keep the
descriptively-named NeitherHeader variant.
- Change "legacy 'X-API-Key'" -> "alternate 'X-API-Key'" in EndpointExtensions.cs and
the BuildPostWithApiKeyHeader/HappyPath doc comments to avoid implying Bearer is
the older transport (Bearer was itself introduced by the prior auth re-arch).
Resolve all 622 issues flagged by the enhanced CommentChecker: add missing
<returns> tags (incl. the standard phrasing on non-generic Task methods),
add missing <summary> tags, and replace misused/redundant <inheritdoc/> on
members that override or implement nothing with real documentation.
Documentation-only — no behavior change; solution builds clean.
Joseph Doherty