Adds AccessControl::check to OverlayOperationEnv::invoke_with_policy in alknet-call
so hub's calls to browser-registered ops are gated by the browser's AccessControl.
Creates src/websocket/overlay.rs with 19 integration tests: overlay scoping (not
PeerCompositeEnv), no PeerId, register_imported/all, overlay_env() routing,
PeerRef::Specific→NOT_FOUND, AccessControl gating, overlay drop on WS close,
ADR-016 abort cascade, bidirectionality, no-ops use-case scoping.
glm-5.2
468bd84f86