[Improve] Harden DCG binary installation (#1060)

* refactor: extract managed binary installation infrastructure

Refs #1055

* fix: address managed binary review feedback

* feat: add destructive command guard binary service

Refs #1056

* test: strengthen DCG binary service coverage

* fix: address DCG service review feedback

* fix: address managed binary review feedback

* test: cover managed binary cleanup boundaries

* fix: address DCG binary service feedback

* fix: finalize managed binary download handling

* test: mirror download stream close events

---------

Co-authored-by: Naved Merchant <14171946+navedmerchant@users.noreply.github.com>