Replace the bare-bones inline HTML in notification, verification, and
admin test emails with a shared branded layout in internal/mail,
matching the web UI's Midnight Cinema theme (dark card shell, wordmark,
mono episode-code badges, white primary CTA). The shell is built for
email clients: tables + inline styles, explicit dark color-scheme,
Outlook-safe button, and a width:100%/max-width pattern so the card
shrinks correctly on phones.
Plain-text bodies, subjects, and the link-free-when-unconfigured
guarantee are unchanged; the admin test email gains an HTML body so the
SMTP test doubles as a design preview.
Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>
