Enhance grammar exercise functionality in VocabLessonView

- Added support for multiple exercise types including multiple choice, gap fill, and transformation.
- Updated UI to display exercise instructions and results with improved styling.
- Implemented logic to handle answer checking based on exercise type, enhancing user interaction.
- Added new translations for exercise-related terms in both English and German.

frontend/src/i18n/locales/de/socialnetwork.json

@@ -359,7 +359,14 @@
                 "forAllLanguages": "Für alle Sprachen",
                 "optional": "Optional",
                 "invalidCode": "Ungültiger Code",
-                "courseNotFound": "Kurs nicht gefunden"
+                "courseNotFound": "Kurs nicht gefunden",
+                "grammarExercises": "Grammatik-Übungen",
+                "noExercises": "Keine Übungen verfügbar",
+                "enterAnswer": "Antwort eingeben",
+                "checkAnswer": "Antwort prüfen",
+                "correct": "Richtig!",
+                "wrong": "Falsch",
+                "explanation": "Erklärung"
             }
         }
     }

frontend/src/i18n/locales/en/socialnetwork.json

@@ -359,7 +359,14 @@
                 "forAllLanguages": "For All Languages",
                 "optional": "Optional",
                 "invalidCode": "Invalid code",
-                "courseNotFound": "Course not found"
+                "courseNotFound": "Course not found",
+                "grammarExercises": "Grammar Exercises",
+                "noExercises": "No exercises available",
+                "enterAnswer": "Enter answer",
+                "checkAnswer": "Check Answer",
+                "correct": "Correct!",
+                "wrong": "Wrong",
+                "explanation": "Explanation"
             }
         }
     }