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/fr/general.json

@@ -148,6 +148,7 @@
             "subscribeLanguage": "Abonnez-vous à la langue",
             "language": "Langue",
             "chapter": "Chapitre",
+            "vocabDictionary": "Dictionnaire",
             "courses": "Cours",
             "course": "Kurs",
             "lesson": "Lektion",

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

@@ -466,6 +466,19 @@
                 "noResults": "Aucun coup sûr.",
                 "error": "La recherche a échoué."
             },
+            "dictionary": {
+                "open": "Dictionnaire",
+                "kicker": "Consulter",
+                "intro": "Tous les termes de vos chapitres. Un seul champ filtre les deux langues par correspondances partielles.",
+                "searchLabel": "Recherche (les deux langues)",
+                "searchPlaceholder": "Fragment dans l’une ou l’autre langue…",
+                "empty": "Aucune entrée.",
+                "loadError": "Impossible de charger le dictionnaire.",
+                "notFound": "Pas d’accès ou introuvable.",
+                "languageTitle": "Dictionnaire : {name}",
+                "courseTitle": "Dictionnaire du cours : {name}",
+                "courseLearningColumn": "Langue apprise (cours)"
+            },
             "courses": {
                 "title": "Cours d'apprentissage des langues",
                 "create": "Créer un cours",