v1.4.523

## Changes

### PR [#2243](https://github.com/danielmiessler/Fabric/pull/2243) by [taljeon](https://github.com/taljeon) and [ksylvan](https://github.com/ksylvan): fix(ai): refresh model catalogs after vendor membership changes

- Fixed model catalogs so they refresh automatically after vendor membership changes, ensuring newly registered vendors are reflected immediately.
- Simplified cache invalidation in `AddVendors` by taking the `modelsMu` lock and clearing the cached models, reducing the change from 463 added lines to 25.
- Reduced `GetModels` to a concise lock-and-read implementation, removing the retry loop and defensive copies.
- Removed the `modelsVersion`, `modelsLoading`, and `modelsDiscovery` machinery, along with `vendorsSnapshot()`, eliminating unnecessary generation tracking and waiter coalescing.
- Reconciled model catalog synchronization with `main`, preserving generation-scoped invalidation behavior while integrating the upstream concurrent-model-read regression fix and its test coverage.