## What changed
- Add the experimental `plugin/search` request with search term, scope, working-directory, cursor, and limit parameters.
- Define paginated results that include each plugin's marketplace name and optional local marketplace path.
- Route the request through app server while returning method-not-found until the search implementation is available.
## Testing
- Add an app-server test that verifies `plugin/search` returns JSON-RPC error `-32601` with the expected not-implemented message.
GitOrigin-RevId: 755400468331f0887f7da7d933195c347aadf6d0