Define recipient variable behavior for multi-recipient emails

When an email template uses variables such as {{recipient.first_name}} and multiple recipients are on the send, define one clear rule for which person those variables refer to.
Implement that rule so preview, sent mail, and builder UX all match—no conflicting “Hello Lisa” vs added-recipient behavior.

Reported behavior: preview can show one name while recipient list suggests another—operators lose trust in merge fields.
Backend personalization flows through renderEmailFromTemplate and per-recipient sends in attik-backend/src/util/functions/emailBuilder/renderEmail.ts, with recipient identity helpers in src/util/functions/actionFlows/recipientIdentity.js (imported from renderEmail.ts). Variable substitution should stay consistent with whatever “primary recipient” or per-recipient pass is chosen.

Backend (attik-backend)

src/util/functions/emailBuilder/renderEmail.ts — merge-field resolution for multi-recipient batch and single-recipient sends; align preview endpoint behavior if one exists alongside production.
src/util/functions/actionFlows/recipientIdentity.js — how “current recipient” is chosen for template blocks.

Frontend (attik-frontend)

Email builder / preview surfaces that call preview APIs—ensure they pass the same recipient context the server uses.

Attik