- Add an APT-only “Held updates” view while keeping held packages excluded from normal and scheduled updates.
- Allow administrators to hold or unhold packages from package details.
- Allow explicitly selected held packages to be updated once, then restore all existing package holds.
- Preserve configured `aptitude` behavior for regular installs while using `apt-get` for the held-package override.
Fixes#2689
e695fbd0c7