Transactional email only sends when RESEND_API_KEY is set; without it
sendEmail() silently no-ops. Combined with requireEmailVerification: true,
that meant every newly registered account was permanently locked out — the
verification link was never delivered and unverified users could not log in.
Verification mail is still sent on signup when email is configured; it is no
longer a barrier to signing in. Re-enable once transactional email is live.
Note: password reset still depends on email delivery, so users who forget a
password remain stuck until RESEND_API_KEY is configured.
Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>
