🐛(i18n) add back the missing email translations

We changed the way we upload the translations to
Crowdin, some translations were missing for the
email templates. We add them back and improve
the tests to make sure we don't forget them again.

src/backend/locale/de_DE/LC_MESSAGES/django.po

@@ -2,8 +2,8 @@ msgid ""
 msgstr ""
 "Project-Id-Version: lasuite-docs\n"
 "Report-Msgid-Bugs-To: \n"
-"POT-Creation-Date: 2025-01-29 13:43+0000\n"
-"PO-Revision-Date: 2025-01-30 10:24\n"
+"POT-Creation-Date: 2025-02-06 15:30+0000\n"
+"PO-Revision-Date: 2025-02-06 15:59\n"
 "Last-Translator: \n"
 "Language-Team: German\n"
 "Language: de_DE\n"
@@ -391,3 +391,24 @@ msgstr "Französisch"
 msgid "German"
 msgstr "Deutsch"
 
+#: core/templates/mail/html/invitation.html:162
+#: core/templates/mail/text/invitation.txt:3
+msgid "Logo email"
+msgstr "Logo-E-Mail"
+
+#: core/templates/mail/html/invitation.html:209
+#: core/templates/mail/text/invitation.txt:10
+msgid "Open"
+msgstr "Öffnen"
+
+#: core/templates/mail/html/invitation.html:226
+#: core/templates/mail/text/invitation.txt:14
+msgid " Docs, your new essential tool for organizing, sharing and collaborating on your documents as a team. "
+msgstr " Docs, Ihr neues unentbehrliches Werkzeug für die Organisation, den Austausch und die Zusammenarbeit in Ihren Dokumenten als Team. "
+
+#: core/templates/mail/html/invitation.html:233
+#: core/templates/mail/text/invitation.txt:16
+#, python-format
+msgid " Brought to you by %(brandname)s "
+msgstr " Erstellt von %(brandname)s "
+