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/migrations/20260331000000-add-vocab-lesson-phase1-fields.cjs

@@ -0,0 +1,44 @@
+'use strict';
+
+module.exports = {
+  async up(queryInterface, Sequelize) {
+    await queryInterface.sequelize.query(`
+      ALTER TABLE community.vocab_course_lesson
+      ADD COLUMN IF NOT EXISTS didactic_mode TEXT,
+      ADD COLUMN IF NOT EXISTS phase_label TEXT,
+      ADD COLUMN IF NOT EXISTS block_number INTEGER,
+      ADD COLUMN IF NOT EXISTS difficulty_weight INTEGER,
+      ADD COLUMN IF NOT EXISTS new_unit_target INTEGER,
+      ADD COLUMN IF NOT EXISTS review_weight INTEGER,
+      ADD COLUMN IF NOT EXISTS is_intensive_review BOOLEAN NOT NULL DEFAULT FALSE;
+
+      COMMENT ON COLUMN community.vocab_course_lesson.didactic_mode IS
+        'Didaktischer Modus der Lektion, z.B. core_input, guided_dialogue, intensive_review oder checkpoint.';
+      COMMENT ON COLUMN community.vocab_course_lesson.phase_label IS
+        'Übergeordnete Lernphase, z.B. quickstart, daily_life oder stabilization.';
+      COMMENT ON COLUMN community.vocab_course_lesson.block_number IS
+        'Inhaltlicher Block für Konsolidierungs- und Wiederholungswellen.';
+      COMMENT ON COLUMN community.vocab_course_lesson.difficulty_weight IS
+        'Grobe relative Schwierigkeit der Lektion von leicht bis schwer.';
+      COMMENT ON COLUMN community.vocab_course_lesson.new_unit_target IS
+        'Empfohlene Zahl neuer Spracheinheiten in dieser Lektion.';
+      COMMENT ON COLUMN community.vocab_course_lesson.review_weight IS
+        'Wie stark Wiederholung in dieser Lektion dominieren soll, typischerweise 0 bis 100.';
+      COMMENT ON COLUMN community.vocab_course_lesson.is_intensive_review IS
+        'Markiert Lektionen, die als intensive Wiederholungsphase gedacht sind.';
+    `);
+  },
+
+  async down(queryInterface, Sequelize) {
+    await queryInterface.sequelize.query(`
+      ALTER TABLE community.vocab_course_lesson
+      DROP COLUMN IF EXISTS is_intensive_review,
+      DROP COLUMN IF EXISTS review_weight,
+      DROP COLUMN IF EXISTS new_unit_target,
+      DROP COLUMN IF EXISTS difficulty_weight,
+      DROP COLUMN IF EXISTS block_number,
+      DROP COLUMN IF EXISTS phase_label,
+      DROP COLUMN IF EXISTS didactic_mode;
+    `);
+  }
+};