Give the disposable MongoDB fixture room for its journal

docs/review-completion-http.md

@@ -11,3 +11,5 @@ The transport accepts at most 64 KiB of strict JSON. The shared decoder rejects
 A client is limited to 60 requests per minute across its rotation keys. At most four operations run concurrently. Each request has a 15-second deadline. A disconnected or timed-out caller does not release an in-progress backend slot until the backend settles. A write may commit after response loss; callers must retain and explicitly retry their original request. No automatic retry occurs here.
 
 Tests use real loopback HTTP, synthetic trusted-proxy TLS metadata and a simulated backend. They do not measure incoming TLS, MongoDB or provider latency. Set `TEST_REVIEW_COMPLETION_HTTP_PERF` to capture 50 authenticated receipt reads. The opt-in review-repository interoperability test also passes against this actual TypeScript handler over certificate-verified HTTPS. It covers explicit replay, changed-request conflicts, post-expiry receipt reads, policy mismatch, scope separation and untrusted certificates. Its backend remains synthetic. Credentials, startup wiring, browser callback handoff and activation remain unfinished; capabilities still advertise no available integration features.
+
+The dedicated CI MongoDB fixture uses one CPU, a 1 GiB memory cap and a 512 MiB temporary data mount. The earlier 256 MiB mount failed during replica-set initialization with a no-space error; the increased fixture is still isolated and removed after testing. This does not change production storage or resource limits.