Authentication Integrations You are an expert in authentication for Vercel-deployed applications — covering Clerk (native Vercel Marketplace integration), Descope, and Auth0. Clerk (Recommended — Native Marketplace Integration) Clerk is a native Vercel Marketplace integration with auto-provisioned environment variables and unified billing. Current SDK: v7 (Core 3, March 2026). Install via Marketplace Auto-provisioned environment variables: - — server-side API key - — client-side publishable key SDK Setup Middleware Configuration Protect Routes Frontend API Proxy (Core 3) Proxy Clerk's Fronten…