🐛 Fix 500 following the password-reset redirect; SMTP via 587

- sessions#new rendered a nonexistent new.turbo_stream when Turbo followed a redirect with a turbo_stream Accept header — serve the HTML template - Resend SMTP moves from port 465 (Hetzner blocks outbound 25/465 by default) to 587 with STARTTLS; the reset mail job was dying with Net::OpenTimeout