Update CDLI Email Template

Summary

This PR introduces a branded HTML email layout for CDLI transactional emails and updates all user-facing mail templates to use it.

Changes Made

Layout

• Rebuilt templates/layout/email/html/default.php with:
  • Centered CDLI logo header
  • Left-aligned body content
  • Branded footer with support contact information
  • Email-safe, table-based HTML structure with inline CSS
• Kept templates/Admin/layout/email/html/default.php in sync with the updated layout.

Email Templates

Updated existing HTML templates:

• templates/email/html/welcome.php
• templates/email/html/resetpassword.php

Added new HTML templates:

• templates/email/html/admin_new_user.php
• templates/email/html/admin_crowdsourcing_privilege.php
• templates/email/html/contribution_declined.php

Mailer & Logo Handling

• Added src/Mailer/BrandedEmailTrait.php to embed the CDLI logo as an inline CID attachment (cid:cdli-logo).
• Updated src/Mailer/UserMailer.php to:
  • Attach the inline logo in deliver() before sending emails.
  • Switch adminNewUser(), adminCrowdsourcingPrivilege(), and contributionDeclined() to Email::MESSAGE_BOTH so both HTML and plain-text versions are sent.

Asset

• Added `app/cake/webroot/images/cdlilogo-email.png` (PNG generated from `cdlilogo.svg` for email client compatibility)

Welcome Email

Password Reset Email