feat(vocab): add language and course dictionary endpoints and UI components

- Implemented `getLanguageDictionary` and `getCourseDictionary` methods in the VocabService to retrieve vocabulary entries filtered by search terms.
- Updated VocabController and vocabRouter to include new routes for accessing language and course dictionaries.
- Enhanced frontend components to navigate to the new dictionary views, including buttons in VocabCourseView and VocabLanguageView.
- Added localization entries for the dictionary feature in multiple languages, ensuring a consistent user experience across the platform.

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

@@ -468,6 +468,19 @@
                 "noResults": "Keine Treffer.",
                 "error": "Suche fehlgeschlagen."
             },
+            "dictionary": {
+                "open": "Wörterbuch",
+                "kicker": "Nachschlagen",
+                "intro": "Alle Begriffe aus deinen Kapiteln. Ein Suchfeld filtert in beiden Sprachen nach Teilwörtern.",
+                "searchLabel": "Suche (beide Sprachen)",
+                "searchPlaceholder": "Teilwort in Lern- oder Muttersprache …",
+                "empty": "Keine Einträge.",
+                "loadError": "Wörterbuch konnte nicht geladen werden.",
+                "notFound": "Kein Zugriff oder nicht gefunden.",
+                "languageTitle": "Wörterbuch: {name}",
+                "courseTitle": "Kurs-Wörterbuch: {name}",
+                "courseLearningColumn": "Lernsprache (Kurs)"
+            },
             "courses": {
                 "title": "Sprachlernkurse",
                 "create": "Kurs erstellen",