Implement the snack.Manager interface for both apt (Debian/Ubuntu) and
dpkg (low-level Debian package tool).
apt wraps apt-get, apt-cache, and dpkg-query for full package management.
dpkg wraps dpkg and dpkg-query for low-level .deb operations.
Upgrade and Update return ErrUnsupportedPlatform for dpkg.
Both packages include:
- Linux implementations with proper error wrapping
- Non-linux build stubs returning ErrUnsupportedPlatform
- Output parsing helpers with tests
- Functional options support (sudo, assume-yes, dry-run)
