Implement vocab course and grammar exercise features in backend and frontend

- Added new course management functionalities in VocabController, including creating, updating, and deleting courses and lessons.
- Implemented enrollment and progress tracking for courses, along with grammar exercise creation and management.
- Updated database schema to include tables for courses, lessons, enrollments, and grammar exercises.
- Enhanced frontend with new routes and views for course listing and details, including internationalization support for course-related texts.
- Improved user experience by adding navigation to courses from the main vocab trainer view.

backend/models/index.js

@@ -129,6 +129,15 @@ import ChatRight from './chat/rights.js';
 import ChatUserRight from './chat/user_rights.js';
 import RoomType from './chat/room_type.js';
 
+// — Vocab Courses —
+import VocabCourse from './community/vocab_course.js';
+import VocabCourseLesson from './community/vocab_course_lesson.js';
+import VocabCourseEnrollment from './community/vocab_course_enrollment.js';
+import VocabCourseProgress from './community/vocab_course_progress.js';
+import VocabGrammarExerciseType from './community/vocab_grammar_exercise_type.js';
+import VocabGrammarExercise from './community/vocab_grammar_exercise.js';
+import VocabGrammarExerciseProgress from './community/vocab_grammar_exercise_progress.js';
+
 const models = {
   SettingsType,
   UserParamValue,
@@ -263,6 +272,15 @@ const models = {
   TaxiMapTileStreet,
   TaxiMapTileHouse,
   TaxiHighscore,
+  
+  // Vocab Courses
+  VocabCourse,
+  VocabCourseLesson,
+  VocabCourseEnrollment,
+  VocabCourseProgress,
+  VocabGrammarExerciseType,
+  VocabGrammarExercise,
+  VocabGrammarExerciseProgress,
 };
 
 export default models;