#89 Restyle Action Web and default email template to match Futex branding

EARS SPEC: - The HITL shall render the Action Web pages (review, OTP, confirm, done, expired) using the Futex brand design system (dark theme, violet/pink gradients, Inter font, glassmorphism). - The HITL shall provide a default email template to the mail-api that matches the Futex brand design system. - The HITL shall ensure the email template renders correctly in major email clients (including Gmail) with clear, clickable primary actions. - The HITL shall ensure the Action Web pages are responsive and accessible.