## What changed
- Add nullable `mustShowInstallationInterstitial` metadata to app-server
`PluginSummary` responses.
- Preserve the remote service value through catalog, installed-plugin cache,
list, read, and share-list paths.
- Return `null` for local plugins and remote responses that omit the field so
clients can fail closed when the policy is unavailable.
## Testing
- Cover `true`, `false`, and missing values across remote summary paths and
app-server plugin endpoints.
GitOrigin-RevId: db79702ee2bfa800a9910d64d933bcabecb3ce70