Add Synthetic (synthetic.new) as a privacy-focused LLM provider
with OpenAI-compatible API, dynamic model catalog via /models
endpoint, and passthrough model support.
- Register provider in providerRegistry.ts with 6 initial models
- Add APIKEY_PROVIDERS entry with verified_user icon (#6366F1)
- Add models listing config for /api/providers/[id]/models endpoint
- passthroughModels enabled for dynamic model catalog