feat(bisaya): update prompts and add migration for food context gap exercise

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

@@ -616,9 +616,14 @@ function buildContextGapExercise(lesson, didactics, pattern) {
     .split(/[.!?]+/)
     .map((step) => step.trim())
     .filter(Boolean);
-  // A multi-step cue is already the concrete scenario.  Do not reduce a
-  // route such as "Diretso. Tuo. Wala. Duol ra." to a bare direction word.
-  const gapTarget = scenarioSteps.length >= 2
+  const cueWordCount = scenarioCue
+    .replace(/[.,?!]/g, ' ')
+    .split(/\s+/)
+    .filter(Boolean)
+    .length;
+  // A multi-step cue or a short word sequence is already the concrete
+  // scenario. Do not reduce a route or a table setting to a bare word.
+  const gapTarget = scenarioSteps.length >= 2 || cueWordCount >= 3
     ? scenarioCue
     : (scenarioPattern || pattern);
   const gapExercise = buildGapExercise(lesson.title, gapTarget);

backend/scripts/create-bisaya-course.js

@@ -374,7 +374,7 @@ const LESSON_DIDACTICS = {
     speakingPrompts: [
       {
         title: 'Auf dem Tisch',
-        prompt: 'Nenne drei Dinge, die auf dem Tisch stehen oder die du essen und trinken möchtest.',
+        prompt: 'Auf dem Tisch stehen Reis, Fisch und Wasser. Ergänze das fehlende Bisaya-Wort.',
         cue: 'Kan-on, isda ug tubig.'
       }
     ],