1.28.0 — the third family, and fragments that become movers

The third family, and fragments that become movers.

RTMPose joins as the third pose extractor on the same trajectory-array contract —
extract_pose_landmarks_rtmpose, riding rtmlib over ONNX runtime with no MMPose
stack, Apache-licensed end to end (pip install musicalgestures[rtmpose]). Its
separate person detector held 100% detection on a dark dance stage where small
single-stage models flickered. All three extractors — MediaPipe, YOLO, RTMPose —
now feed the same detector-agreement tooling, and the posetools docs page carries
the measured which-to-reach-for guidance.

associate_fragments chains identity-track fragments into persistent movers using
position and time only, under an exclusivity constraint and a plausibility bound
measured from the material itself — and it refuses where honesty demands: a
crossing at a fragment boundary becomes a recorded break for a human to
adjudicate, never a guess. The design document records both the method and its own
measured mispredictions.

Full details in the CHANGELOG.