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/en/general.json

@@ -148,6 +148,7 @@
             "subscribeLanguage": "Subscribe to language",
             "language": "Language",
             "chapter": "Chapter",
+            "vocabDictionary": "Dictionary",
             "courses": "Courses",
             "course": "Course",
             "lesson": "Lesson",

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

@@ -468,6 +468,19 @@
                 "noResults": "No results.",
                 "error": "Search failed."
             },
+            "dictionary": {
+                "open": "Dictionary",
+                "kicker": "Lookup",
+                "intro": "All terms from your chapters. One field filters both languages by partial matches.",
+                "searchLabel": "Search (both languages)",
+                "searchPlaceholder": "Part of a word in either language…",
+                "empty": "No entries.",
+                "loadError": "Could not load the dictionary.",
+                "notFound": "No access or not found.",
+                "languageTitle": "Dictionary: {name}",
+                "courseTitle": "Course dictionary: {name}",
+                "courseLearningColumn": "Learning language (course)"
+            },
             "courses": {
                 "title": "Language Learning Courses",
                 "create": "Create Course",