Auth:RequireEmailVerification (default off) gates whether local
register requires confirming email before login. OAuth new-user paths
are untouched -- Google/Microsoft already assert a verified email.
Adds verify-email and resend-verification-email endpoints, mirroring
the existing reset-password enumeration-avoidance and rate-limiting
patterns, plus a login-embedded resend affordance and a verify-email
landing page on the frontend.
Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>
cesnimda