add rfdetr_v9.safetensors (MLX runtime, sibling of rfdetr_v9.onnx)

add rfdetr_v9.onnx — retrained on 905-img augmented bench, 0% FP across 42+ surfaces at thr 0.50

examples: end-to-end inference + redaction demo

notice: attribution to RF-DETR + WebPII

license: CC BY-NC 4.0

docs: model card with bench numbers + privacy contract

model: rfdetr_v8 ONNX (108 MB)

initial commit