feat(bisaya-course): enhance grammar focus and drills for lesson content

- Added functions to normalize and build grammar curriculum focus entries, improving the structure and clarity of grammar lessons.
- Implemented logic to merge existing grammar focus with newly defined curriculum focus, ensuring comprehensive coverage of key grammar points.
- Introduced new drills for practicing past and future tense constructions, enhancing student engagement and understanding of temporal aspects in Bisaya.
- Updated the `createBisayaCourseContent` function to incorporate these enhancements, ensuring lessons are enriched with relevant grammar exercises.

backend/scripts/create-bisaya-course-content.js

@@ -206,6 +206,117 @@ function mergeCorePatternsForLesson(didactics, exerciseDerived, minCount = 8) {
   return out;
 }
 
+function normalizeGrammarFocusEntry(entry) {
+  if (!entry || typeof entry !== 'object') return null;
+  const title = normalizeText(entry.title || '');
+  const text = normalizeText(entry.text || '');
+  const example = normalizeText(entry.example || '');
+  if (!title || !text) return null;
+  return { title, text, ...(example ? { example } : {}) };
+}
+
+function buildGrammarCurriculumFocus(lesson) {
+  const lessonNumber = Number(lesson?.lessonNumber || 0);
+  const title = normalizeText(lesson?.title || '').toLowerCase();
+  const out = [];
+
+  if (lessonNumber >= 1 && lessonNumber <= 10) {
+    out.push({
+      title: 'Kernaussage + Ergänzung',
+      text: 'Im Alltag funktionieren kurze Muster am besten: Aussage zuerst, dann Ort/Zeit/Detail.',
+      example: 'Naa ko sa balay. / Moadto ko unya.'
+    });
+  }
+
+  if (lessonNumber >= 11 && lessonNumber <= 20) {
+    out.push({
+      title: 'Präsens, Vergangenheit, Zukunft',
+      text: 'In diesem Kurs arbeitest du mit klaren Zeitmarkern: Gegenwart über Kontext oder nag-/ga-, Vergangenheit oft mit ni-, Zukunft mit mo-.',
+      example: 'Nagkaon ko. / Ni-kaon ko. / Mo-kaon ko.'
+    });
+  }
+
+  if (title.includes('zeitformen')) {
+    out.push(
+      {
+        title: 'Vergangenheit mit ni-',
+        text: 'ni- markiert häufig abgeschlossene Handlungen in der Vergangenheit.',
+        example: 'Ni-adto ko. (Ich bin gegangen.)'
+      },
+      {
+        title: 'Zukunft/Absicht mit mo-',
+        text: 'mo- markiert häufig Zukünftiges oder eine geplante Handlung.',
+        example: 'Mo-adto ko. (Ich werde gehen.)'
+      }
+    );
+  }
+
+  if (lessonNumber >= 21) {
+    out.push({
+      title: 'Aspekt statt starrer Zeiten',
+      text: 'Bisaya nutzt im Alltag oft Aspektmarker und Kontext statt fixer Tempusformen. Zeitwörter wie karon, ganiha, ugma helfen bei der Einordnung.',
+      example: 'Niadto ko ganiha. / Moadto ko ugma.'
+    });
+  }
+
+  return out.map((entry) => normalizeGrammarFocusEntry(entry)).filter(Boolean);
+}
+
+function mergeGrammarFocusForLesson(existingFocus, curriculumFocus) {
+  const out = [];
+  const seen = new Set();
+  const pushUnique = (entry) => {
+    const normalized = normalizeGrammarFocusEntry(entry);
+    if (!normalized) return;
+    const key = `${normalized.title.toLowerCase()}|${normalized.text.toLowerCase()}`;
+    if (seen.has(key)) return;
+    seen.add(key);
+    out.push(normalized);
+  };
+  (Array.isArray(existingFocus) ? existingFocus : []).forEach(pushUnique);
+  (Array.isArray(curriculumFocus) ? curriculumFocus : []).forEach(pushUnique);
+  return out;
+}
+
+function buildZeitformenDrills(lessonTitle) {
+  return [
+    {
+      exerciseTypeName: 'transformation',
+      title: `${lessonTitle}: Vergangenheit bilden`,
+      instruction: 'Übersetze den Satz ins Bisaya.',
+      questionData: {
+        type: 'transformation',
+        text: 'Ich bin zum Markt gegangen.',
+        sourceLanguage: 'Deutsch',
+        targetLanguage: 'Bisaya'
+      },
+      answerData: {
+        type: 'transformation',
+        correct: 'Ni-adto ko sa merkado.',
+        alternatives: ['Niadto ko sa merkado.', 'Niadto ko sa merkado.']
+      },
+      explanation: 'Vergangenheit wird hier mit ni- markiert.'
+    },
+    {
+      exerciseTypeName: 'transformation',
+      title: `${lessonTitle}: Zukunft bilden`,
+      instruction: 'Übersetze den Satz ins Bisaya.',
+      questionData: {
+        type: 'transformation',
+        text: 'Ich werde morgen nach Hause gehen.',
+        sourceLanguage: 'Deutsch',
+        targetLanguage: 'Bisaya'
+      },
+      answerData: {
+        type: 'transformation',
+        correct: 'Mo-adto ko sa balay ugma.',
+        alternatives: ['Moadto ko sa balay ugma.', 'Mo uli ko ugma.']
+      },
+      explanation: 'Zukünftiges wird hier mit mo- plus Zeitwort (ugma) markiert.'
+    }
+  ];
+}
+
 function sanitizeGapFillHintText(lessonTitle, text, answers, glossLookup) {
   const source = String(text || '');
   const normalizedAnswers = Array.isArray(answers)
@@ -613,6 +724,9 @@ function generateExercisesFromDidactics(lesson) {
       buildTaskSentenceExercise(lesson, didactics, patternB),
       buildSpeakingExercise(lesson.title, didactics, patternA)
     ];
+    if (String(lesson.title || '').toLowerCase().includes('zeitformen')) {
+      generated.push(...buildZeitformenDrills(lesson.title));
+    }
   } else if (lesson.lessonType === 'review' || lesson.didacticMode === 'intensive_review') {
     generated = [
       buildReviewChoiceExercise(lesson, didactics, patternA, lessonPool),
@@ -4575,6 +4689,13 @@ async function createBisayaCourseContent() {
       
       // Erstelle Übungen
       const lessonDidactics = getLessonDidactics(lesson);
+      const mergedGrammarFocus = mergeGrammarFocusForLesson(
+        lessonDidactics.grammarFocus,
+        buildGrammarCurriculumFocus(lesson)
+      );
+      if (mergedGrammarFocus.length > 0) {
+        await lesson.update({ grammarFocus: mergedGrammarFocus });
+      }
       const derivedCorePatterns = deriveLessonCorePatternsFromExercises(exercises);
       const mergedCorePatterns = mergeCorePatternsForLesson(lessonDidactics, derivedCorePatterns, 8);
       if (mergedCorePatterns.length >= 8) {