feat(bisaya-course): enhance phase 4 didactics with new learning goals and speaking prompts

- Expanded the BISAYA_PHASE4_DIDACTICS by adding new learning goals, core patterns, speaking prompts, and practical tasks to improve language acquisition.
- Updated the course content generation scripts to incorporate the new lesson structures and ensure alignment with the latest didactic updates.
- Enhanced the logic for generating exercises based on lesson types, introducing additional situational and speaking exercises for advanced lessons.

backend/scripts/update-bisaya-didactics.js

@@ -17,6 +17,7 @@ import {
   BISAYA_RELATIONSHIP_ANCHOR_DIDACTICS
 } from './bisaya-course-plan-24-43.js';
 import { BISAYA_PHASE3_DIDACTICS } from './bisaya-course-phase3-extension.js';
+import { BISAYA_PHASE4_DIDACTICS } from './bisaya-course-phase4-extension.js';
 
 /** Alte Kurstitel → aktueller Schlüssel in LESSON_DIDACTICS (bestehende Datenbanken). */
 export const LEGACY_DIDACTICS_TITLE_MAP = {
@@ -488,7 +489,8 @@ export const LESSON_DIDACTICS = {
   },
   ...BISAYA_RELATIONSHIP_ANCHOR_DIDACTICS,
   ...BISAYA_DIDACTICS_24_43,
-  ...BISAYA_PHASE3_DIDACTICS
+  ...BISAYA_PHASE3_DIDACTICS,
+  ...BISAYA_PHASE4_DIDACTICS
 };
 
 function resolveDidacticsForLesson(lesson) {