fix#13397fix#14011
#### PR Dependency Tree
* **PR #14502** 👈
This tree was auto-generated by
[Charcoal](https://github.com/danerwilliams/charcoal)
<!-- This is an auto-generated comment: release notes by coderabbit.ai
-->
## Summary by CodeRabbit
* **New Features**
* Centralized CORS policy with dynamic origin validation applied to
server and realtime connections
* Improved sign-in flows with contextual, localized error hints and
toast notifications
* Centralized network-error normalization and conditional OAuth provider
fetching
* **Bug Fixes**
* Better feedback for self-hosted connection failures and clearer
authentication error handling
* More robust handling of network-related failures with user-friendly
messages
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