Introduce getAppBaseUrl() in packages/api/src/lib/app-base-url.ts:
- Reads NEXTAUTH_URL (trimmed, trailing slash stripped)
- production: throws if NEXTAUTH_URL is missing/empty so broken
localhost links in emails are caught at runtime, not silently sent
- development/test: falls back to http://localhost:3100 with a
one-time console.warn
Replace the duplicated inline fallback in:
- packages/api/src/router/invite.ts (invite email link)
- packages/api/src/router/auth.ts (password reset email link)
Extend GET /api/health to report:
"baseUrl": { "configured": bool, "isLocalhost": bool }
so deployment checks can detect a misconfigured NEXTAUTH_URL.
Co-Authored-By: claude-flow <ruv@ruv.net>
