🚸(backend) display recording owners directly in admin list view

Show recording owner(s) directly in admin list interface to speed up
troubleshooting. Previously required clicking into each object to identify
owner. Handles multiple owners (rare) by displaying a default message.

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

@@ -8,7 +8,7 @@ msgid ""
 msgstr ""
 "Project-Id-Version: PACKAGE VERSION\n"
 "Report-Msgid-Bugs-To: \n"
-"POT-Creation-Date: 2025-05-16 17:04+0000\n"
+"POT-Creation-Date: 2025-05-26 10:50+0000\n"
 "PO-Revision-Date: YEAR-MO-DA HO:MI+ZONE\n"
 "Last-Translator: FULL NAME <EMAIL@ADDRESS>\n"
 "Language-Team: LANGUAGE <LL@li.org>\n"
@@ -29,6 +29,14 @@ msgstr "Berechtigungen"
 msgid "Important dates"
 msgstr "Wichtige Daten"
 
+#: core/admin.py:143
+msgid "No owner"
+msgstr "Kein Eigentümer"
+
+#: core/admin.py:146
+msgid "Multiple owners"
+msgstr "Mehrere Eigentümer"
+
 #: core/api/serializers.py:63
 msgid "You must be administrator or owner of a room to add accesses to it."
 msgstr ""