* test(odm): pin gcs source status-to-error-class mapping
The native GCS backend classifies every failure from the HTTP status
alone, because GCS states its error code in a body this backend never
reads. Only NotFound is negative-cached and only a retryable class may be
re-sent, so cover 401/403 -> AccessDenied, 429/503 -> Throttled,
500/502 -> ServerError and 404 -> NotFound over both HEAD and GET.
* ci(odm): require the source-backend contract tests in test-and-lint
The shared contract tests already run in ci/test-and-lint, but only
because gcs is a rustfs default feature; nothing failed if that
selection went away. Pin the S3, Azure and native GCS contracts in the
core required-test manifest so a lost selection fails the lane.
* test(ecstore): require core invariant tests in existing CI lane
* test(ci): require a fresh core JUnit report
* test(ecstore): match sealed context fixture map type
Zhengchao An