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/german-for-bisaya-phase2-pedagogy.js

@@ -63,3 +63,43 @@ export function getGermanForBisayaLessonPedagogy(lessonNumber, lessonType, lesso
     isIntensiveReview: lessonType === 'review'
   };
 }
+
+export function getGermanForBisayaProgressTargets(lessonData, pedagogy) {
+  const baseMinutes = Number(lessonData?.targetMin || 18);
+  const baseScore = Number(lessonData?.targetScore || 80);
+  const lessonNumber = Number(lessonData?.num || 1);
+  const lessonType = String(lessonData?.type || '');
+  const didacticMode = String(pedagogy?.didacticMode || '');
+  const isCheckpoint = String(lessonData?.title || '').toLowerCase().includes('checkpoint');
+
+  // Spuerbar steilere Progression: spaetere Wochen bekommen mehr Produktionszeit
+  // und hoehere Zielwerte, ohne den Einstieg zu ueberfrachten.
+  let minutesBump = 0;
+  if (lessonNumber >= 61 && lessonNumber <= 90) minutesBump += 2;
+  if (lessonNumber >= 91 && lessonNumber <= 120) minutesBump += 4;
+  if (lessonNumber >= 121) minutesBump += 6;
+
+  if (lessonType === 'conversation' && lessonNumber >= 91) minutesBump += 2;
+  if (lessonType === 'review') minutesBump += 3;
+  if (isCheckpoint) minutesBump += 2;
+
+  let scoreBump = 0;
+  if (lessonNumber >= 61 && lessonNumber <= 90) scoreBump += 2;
+  if (lessonNumber >= 91 && lessonNumber <= 120) scoreBump += 4;
+  if (lessonNumber >= 121) scoreBump += 6;
+
+  if (lessonType === 'grammar') scoreBump += 2;
+  if (lessonType === 'review') scoreBump += 2;
+  if (didacticMode === 'contrast_training') scoreBump += 1;
+  if (isCheckpoint) scoreBump += 3;
+
+  const targetMinutes = Math.min(45, baseMinutes + minutesBump);
+  const targetScorePercent = lessonType === 'culture'
+    ? 0
+    : Math.min(96, baseScore + scoreBump);
+
+  return {
+    targetMinutes,
+    targetScorePercent
+  };
+}