## 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
## What changed
- Stop writing `last_updated` and `last_revision` to marketplace entries in
`config.toml`; keep the activated revision in
`.codex-marketplace-install.json` instead.
- Use installed marketplace metadata to detect up-to-date checkouts.
- Snapshot the installed marketplace before activation and roll back a stale
upgrade if another installation changed the destination concurrently.
## Testing
- Verify marketplace add and upgrade operations leave `config.toml` unchanged.
- Cover restoring a newer concurrently installed marketplace when a stale
activation is rejected.
GitOrigin-RevId: 10942c3fc7c6c3f68b7d5953e8c1b5e86bf71866
## Summary
Move the marketplace remove implementation into shared core logic so
both the CLI command and follow-up app-server RPC can reuse the same
behavior.
This change:
- adds a shared `codex_core::plugins::remove_marketplace(...)` flow
- moves validation, config removal, and installed-root deletion out of
the CLI
- keeps the CLI as a thin wrapper over the shared implementation
- adds focused core coverage for the shared remove path
## Validation
- `just fmt`
- focused local coverage for the shared remove path
- heavier follow-up validation deferred to stacked PR CI
