breathe-apprpc

The AppRpcCluster Cluster impl — breathe's APP-ADMIN-ENDPOINT I/O boundary (Go GOMEMLIMIT, Kafka/RabbitMQ queue prefetch, adaptive-concurrency bounds). The hands that read + carve a running app's live runtime knobs via its admin HTTP endpoint. Handles LimitLayout::ApiCall { endpoint, command }; RestartFree by construction (the knob applies live). Side effects abstracted behind the AppRpcEnv trait (the typed-spec-triplet testability seam).