feat(admin): add potential fathers retrieval for character management

- Implemented a new method in AdminService to fetch potential fathers for a given character based on existing relationships.
- Updated AdminController to expose this functionality via a new API endpoint.
- Enhanced adminRouter to include the route for retrieving potential fathers.
- Modified frontend components to allow selection of potential fathers during pregnancy and birth management.
- Updated internationalization files to include new translation keys related to father selection.

backend/sql/extend_bisaya_course_phase5_to_stabilization.sql

@@ -0,0 +1,11 @@
+UPDATE community.vocab_course AS course
+SET
+  title = 'Bisaya für Familien - Alltag & Stabilisierung',
+  description = 'Lerne Bisaya (Cebuano) praxisnah für den Familienalltag. Der Pfad verbindet Schnellstart, Alltagsmodule und Stabilisierungsblöcke mit Spiralwiederholung, Fehlertraining und freier Produktion.'
+FROM community.vocab_language AS language
+WHERE course.language_id = language.id
+  AND language.name = 'Bisaya';
+
+-- Für die neuen Lektionen 121-150 wird das Skript
+-- backend/scripts/extend-bisaya-course-phase5.js empfohlen, weil dort
+-- auch die JSON-Felder der Lektionen konsistent gepflegt werden.