## What changed
- Move remote plugin install and uninstall orchestration from the app server into shared `PluginsManager` APIs.
- Keep cache and backend mutations coordinated by the installed-plugin sync gate, and retain install outcomes long enough to protect newly materialized bundles during downstream setup.
- Return structured operation errors and outcomes so callers can preserve JSON-RPC error mapping, telemetry, cache refreshes, and OAuth setup.
## Testing
- Add regression coverage that verifies uninstall holds the mutation gate, preserves the local cache when the backend operation fails, and refreshes installed state after a successful uninstall.
GitOrigin-RevId: de39f19a4e61c6e9c76ddc2c65d2ac130a4b7f88
ef76e6ac30