feat(bisaya-course): add didactics fragments for "Haus & Familie" lessons

- Introduced comprehensive didactics snippets for the "Haus & Familie" lesson, including learning goals, core patterns, grammar focus, speaking prompts, and practical tasks.
- Updated the lesson retrieval logic to incorporate these new fragments as a fallback for core patterns, enhancing the robustness of lesson content delivery.
- Modified the vocab service to utilize the new didactics fragments, ensuring a seamless integration into the existing lesson structure.

backend/scripts/update-bisaya-didactics.js

@@ -9,6 +9,7 @@
 import { sequelize } from '../utils/sequelize.js';
 import VocabCourseLesson from '../models/community/vocab_course_lesson.js';
 import { getBisayaLessonPedagogy } from './bisaya-course-phase2-pedagogy.js';
+import { BISAYA_DIDACTICS_FRAGMENTS } from './bisaya-course-phase1.js';
 
 /** Alte Kurstitel → aktueller Schlüssel in LESSON_DIDACTICS (bestehende Datenbanken). */
 export const LEGACY_DIDACTICS_TITLE_MAP = {
@@ -140,6 +141,7 @@ export const LESSON_DIDACTICS = {
       { title: 'Gesprächspraxis', text: 'Spiele einen kurzen Familienaustausch mit Frage, Antwort und Fürsorge nach.' }
     ]
   },
+  'Haus & Familie': BISAYA_DIDACTICS_FRAGMENTS['Haus & Familie'],
   'Gefühle & Zuneigung': {
     learningGoals: [
       'Wichtige Gefühle und Zuneigungsformeln sicher unterscheiden.',