🔒 GDPR data-privacy-email template + getMail large-export fallback

[PierreBrisorgueil]

Restore the email-delivery path for large exports, with a safe inline fallback.

Scope

• Restore config/templates/data-privacy-email.html (handlebars; params firstName, exportedAt).
• Wire getMail in users.data.controller to mailer.sendMail with the JSON export as a 25 MB-capped attachment.
• Fall back to inline JSON when the mailer is unconfigured OR the export exceeds the cap (never silently email to nowhere).

DoD

• getMail emails when configured, returns inline when not; size-gate test.
• /verify green.

Depends on: GDPR export+erasure controller.

Created via /dev:issue