Use PM for engine binaries, dependent runtime archives, and model files.
Keep one operation-owned pause event through installation and download.
Report whole-plan bytes and retain paused jobs across desktop remounts.
Preserve the completed lm-pm worktree as its own integration parent.
The owning session verified focused Python and desktop tests, actual
Windows ARM64 CUDA downloads, and rendered pause/resume controls.
Combined verification with the safety repairs follows in the merge.