refactor: remove sample_pose_cache module and streamline pose processing in pipeline

refactor: change default delegate to CPU in MediaPipePoseBackend and update tests accordingly

refactor(mediapipe): simplify GPU delegate preference logic and remove unused CUDA visibility check

refactor(mediapipe): enhance MediaPipePoseBackend to prefer tasks on GPU and improve delegate handling

fix(hf-spaces): install mediapipe native libraries

feat(pose)!: use coco17 3d router features

feat(hf): use ZeroGPU for analysis

perf(pose): read dense video frames sequentially

feat(pose): add pluggable pose backends

feat(pose): use dense frames for real pose extraction

test(pose): allow src path imports in pose tests

feat(pose): add pluggable pose backends