Mobile app sign-in now works reliably
Fixes mobile app sign-in against the shared backend, and stops Support's knowledge base from silently breaking on the wrong AI provider.
The mobile app can now authenticate against the same backend as the web app. Native sign-in callbacks from the SharpOS and Expo apps are now trusted by our auth system, so logging in from the mobile app works the way it's supposed to.
Support also got a fix to how it stores its knowledge base. You can still use OpenRouter for the chat itself, but the knowledge base's embeddings now have to come from OpenAI. If an organization had the old, unsupported combination saved, it gets pointed back to OpenAI automatically so the next save re-indexes cleanly instead of quietly failing.