v1.4.7 — first-class --omni-backend flag
Promotes the VMLX_OMNI_BACKEND env override to a CLI flag so the panel + Swift Settings UI can flip the Nemotron-Omni multimodal path between Stage-1 (bit-exact PyTorch bridge, default, correct) and Stage-2 (native MLX RADIO + Parakeet, ~15-21x faster encoders + 82 tok/s decode on M4 Max). Stage-2 default-off pending Wave-4 quality validation. Qwen 3.6 VL audit confirmed fully wired both Python + Swift sides.