* feat: add server conformance tests for SEP-2575
* refactor and add new checks
* Fix stateless scenario source field and report SKIPPED for inapplicable capability checks
- Add the required `source` field (DRAFT) so the scenario typechecks and is
selectable via --spec-version. Without it the class did not satisfy the
ClientScenario interface and s.source was dereferenced by the spec-version
filter at list time.
- Teach runCheck about a SKIPPED status and use it for the two client-capability
checks when the server does not return -32003, instead of reporting a green
PASS for a requirement that was never exercised.
* Remove unimplemented placeholder checks from stateless server scenario
The subscriptions/listen, statelessness-invariant, list-changed and
disconnect-is-cancel checks emitted SUCCESS without probing the server,
which inflated coverage in the traceability report. Drop them until they
have real assertions; the corresponding rows remain declared in
src/seps/sep-2575.yaml so traceability shows them as not-yet-covered.
Also fix the checkErrorId helper to push under the
sep-2575-http-server-error-jsonrpc-id slug so its failure path actually
short-circuits the aggregate SUCCESS check at the end of the scenario.
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Co-authored-by: Paul Carleton <paulc@anthropic.com>