- Create api/relay.ts: Vercel serverless function handler that reuses
relay logic from src/lib/relay-utils.ts and src/middleware/
- Export default fetch handler (no Bun.serve()) for Vercel Functions
- Fix vercel.json: use @vercel/node@5 runtime with proper routing via
rewrites to catch all traffic to the relay handler
- Remove stale buildCommand/outputDirectory (Vercel handles function builds)
Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>