Support load balancer geo-routing with custom domains

Problem When using a custom domain (e.g., api.myapp.com), requests bypass Supabase's load balancer entirely. This means: • ❌ No automatic geo-routing to nearest read replica • ❌ No automatic health checks / failover • ❌ Must implement application-level routing From the [docs]( > "If you use a custom domain, requests will not be routed through the load balancer." Why Custom Domains Matter Custom domains are required for professional OAuth flows. Without them: • Google OAuth shows "Signing in to xyz.supabase.co" (looks like phishing) • Users don't trust unfamiliar domains in auth consent screens Current Workaround The only option is a hybrid approach: • Custom domain for Auth (OAuth consent screen) • Load balancer URL for Data API reads This requires: • Two Supabase clients in the application • Manual session forwarding between them • Extra complexity that Supab…