Moves probeDeviceOptionsDual, applyDuplexSetup, applySplitSetup, and
teardownSplitMode verbatim into src/audio/engine/DeviceSetup.{h,cpp}. The
component holds references to the two device managers + EngineState and owns
no lifetime; engine-owned collaborators (monitor chain, split output ring +
counters, output callback registration) are passed by reference per call.
setAudioDevices stays on the facade as the orchestrator. The public
DeviceOptions/DeviceConfig/DeviceConfigResult shapes move to the slopsmith
namespace with using-aliases on AudioEngine, so the NodeAddon spelling is
unchanged.
Lands the deep-read §7 dedupe structurally: the <=0.5 rate tolerance,
midpoint-rounding fail-closed candidate, and empty-name→first-enumerated
resolution now exist once (RateMatch.h — JUCE-free + unit-tested boundary
cases — and DeviceSetup::resolveDeviceName/rateSupportedBy) instead of three
hand-synced copies.
Full device-matrix validation (WASAPI shared/exclusive, ASIO, dual-type
split) rides the next tester build per the plan's phase-4 gate.
Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>