fix(email): parse JSON-encoded language setting before using as locale

general_default_language is stored as a JSON string (e.g. "\"pt\"").
getRecipientLanguage() returned the raw value including quotes, causing
the translation lookup to miss every match and fall back to English.

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

backend/src/services/emailProcessor.js

@@ -116,7 +116,9 @@ async function getRecipientLanguage(email, eventId = null) {
       .where('setting_key', 'general_default_language')
       .first();
     if (langSetting && langSetting.setting_value) {
-      return langSetting.setting_value;
+      let lang = langSetting.setting_value;
+      try { lang = JSON.parse(lang); } catch (_) {}
+      if (typeof lang === 'string' && lang.trim()) return lang.trim();
     }
   } catch (error) {
     logger.error('Error fetching app settings language:', error);