fix(email): resolve recipient language from the queue row's event_id, not just email_data

Language priority is event.language → customer preferred_language → app default
→ … → en, but it was keyed on email_data.eventId, which only queueEmail injects.
Direct email_queue inserts (e.g. the gallery-publish "notify customer" path) set
the event_id COLUMN but not email_data.eventId, so those mails skipped
event.language and fell through to the default — e.g. a gallery-ready mail in EN
while the same event's pre-event reminder (sent via queueEmail) was DE.

The processor now backfills emailData.eventId from the authoritative event_id
column before rendering, so every send path resolves language from the event
consistently.

backend/src/services/emailProcessor.js

@@ -864,6 +864,15 @@ async function processEmailQueue({ ignoreSchedule = false, limit = 10, onlyId =
           ? JSON.parse(email.email_data || '{}')
           : email.email_data || {};
 
+        // Language is resolved from emailData.eventId (event.language is the top
+        // priority). queueEmail injects it, but direct email_queue inserts (e.g.
+        // the gallery-publish notification) only set the event_id COLUMN — so
+        // backfill from the authoritative column so every send path resolves the
+        // recipient language from the event consistently.
+        if (emailData.eventId == null && email.event_id != null) {
+          emailData.eventId = email.event_id;
+        }
+
         const sendResult = await sendTemplateEmail(
           email.recipient_email,
           email.email_type,