- Tasks page: the engine box "N models" count now has a hover tooltip
  listing every loaded model key on that engine (dotted underline + help
  cursor); "no models loaded" when empty.
- Models page: models loaded on a non-primary engine were shown as idle.
  /admin/api/model-loaded-status is served by the primary engine and only
  reported its own pool. Added a front-proxy interceptor that proxies to
  the primary then unions in every other engine's loaded_models, mirroring
  the existing /admin/api/engines and /admin/api/status aggregation.
Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>