Adapt a NativeConsoleMixer to the engine's NativeOutputRouteControl seam
(#158, phase 2): the reconcile lays each EXTRA MAIN output destination on its OWN native
out_<idx> port (syncExtraRoutes / routePorts) and pushes each route's per-destination
trim into the C stage (setRouteTrim → setOutputRoute). routePorts drops route 0 (the
primary keeps main_L/main_R). Extracted so it unit-tests with a fake native node.
Adapt a NativeConsoleMixer to the engine's NativeOutputRouteControl seam (#158, phase 2): the reconcile lays each EXTRA MAIN output destination on its OWN native
out_<idx>port (syncExtraRoutes/routePorts) and pushes each route's per-destination trim into the C stage (setRouteTrim→setOutputRoute).routePortsdrops route 0 (the primary keeps main_L/main_R). Extracted so it unit-tests with a fake native node.