PCM_RING_FRAMES 16→50 (320ms→1000ms capacity) and
PREBUFFER_FRAMES 3→15 (60ms→300ms prebuffer) to match
LXST-kt's buffering strategy. Interop test suite confirms
zero underruns with ±100ms jitter at these settings.
Also adds tests/interop/ with 48 Python tests verifying
wire format, codec round-trip, and pipeline compatibility
between Pyxis, Python LXST, and LXST-kt implementations.
Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>