## Why
Removing a base-user marketplace must not delete a snapshot that is still
referenced by another enabled configuration layer.
## What changed
- Load the current configuration stack for marketplace commands in the CLI and
app server.
- Reject removal when a matching marketplace is defined by another enabled
layer, and identify the configuration source that must be updated instead.
- Allow cleanup of an installed marketplace snapshot even when no base-user
entry exists.
## Testing
Cover project, enterprise-managed, system, and session-flag configurations, as
well as snapshot-only removal through the CLI and app server.
GitOrigin-RevId: 4f0853a40c2b5fae0410696b79eee4284239c7a9
