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/community/vocab_course.js

@@ -0,0 +1,69 @@
+import { Model, DataTypes } from 'sequelize';
+import { sequelize } from '../../utils/sequelize.js';
+
+class VocabCourse extends Model {}
+
+VocabCourse.init({
+    id: {
+        type: DataTypes.INTEGER,
+        primaryKey: true,
+        autoIncrement: true
+    },
+    ownerUserId: {
+        type: DataTypes.INTEGER,
+        allowNull: false,
+        field: 'owner_user_id'
+    },
+    title: {
+        type: DataTypes.TEXT,
+        allowNull: false
+    },
+    description: {
+        type: DataTypes.TEXT,
+        allowNull: true
+    },
+    languageId: {
+        type: DataTypes.INTEGER,
+        allowNull: false,
+        field: 'language_id'
+    },
+    difficultyLevel: {
+        type: DataTypes.INTEGER,
+        allowNull: false,
+        defaultValue: 1,
+        field: 'difficulty_level'
+    },
+    isPublic: {
+        type: DataTypes.BOOLEAN,
+        allowNull: false,
+        defaultValue: false,
+        field: 'is_public'
+    },
+    shareCode: {
+        type: DataTypes.TEXT,
+        allowNull: true,
+        unique: true,
+        field: 'share_code'
+    },
+    createdAt: {
+        type: DataTypes.DATE,
+        allowNull: false,
+        defaultValue: DataTypes.NOW,
+        field: 'created_at'
+    },
+    updatedAt: {
+        type: DataTypes.DATE,
+        allowNull: false,
+        defaultValue: DataTypes.NOW,
+        field: 'updated_at'
+    }
+}, {
+    sequelize,
+    modelName: 'VocabCourse',
+    tableName: 'vocab_course',
+    schema: 'community',
+    timestamps: true,
+    underscored: true
+});
+
+export default VocabCourse;

backend/models/community/vocab_course_enrollment.js

@@ -0,0 +1,37 @@
+import { Model, DataTypes } from 'sequelize';
+import { sequelize } from '../../utils/sequelize.js';
+
+class VocabCourseEnrollment extends Model {}
+
+VocabCourseEnrollment.init({
+    id: {
+        type: DataTypes.INTEGER,
+        primaryKey: true,
+        autoIncrement: true
+    },
+    userId: {
+        type: DataTypes.INTEGER,
+        allowNull: false,
+        field: 'user_id'
+    },
+    courseId: {
+        type: DataTypes.INTEGER,
+        allowNull: false,
+        field: 'course_id'
+    },
+    enrolledAt: {
+        type: DataTypes.DATE,
+        allowNull: false,
+        defaultValue: DataTypes.NOW,
+        field: 'enrolled_at'
+    }
+}, {
+    sequelize,
+    modelName: 'VocabCourseEnrollment',
+    tableName: 'vocab_course_enrollment',
+    schema: 'community',
+    timestamps: false,
+    underscored: true
+});
+
+export default VocabCourseEnrollment;

backend/models/community/vocab_course_lesson.js

@@ -0,0 +1,93 @@
+import { Model, DataTypes } from 'sequelize';
+import { sequelize } from '../../utils/sequelize.js';
+
+class VocabCourseLesson extends Model {}
+
+VocabCourseLesson.init({
+    id: {
+        type: DataTypes.INTEGER,
+        primaryKey: true,
+        autoIncrement: true
+    },
+    courseId: {
+        type: DataTypes.INTEGER,
+        allowNull: false,
+        field: 'course_id'
+    },
+    chapterId: {
+        type: DataTypes.INTEGER,
+        allowNull: true,
+        field: 'chapter_id'
+    },
+    lessonNumber: {
+        type: DataTypes.INTEGER,
+        allowNull: false,
+        field: 'lesson_number'
+    },
+    title: {
+        type: DataTypes.TEXT,
+        allowNull: false
+    },
+    description: {
+        type: DataTypes.TEXT,
+        allowNull: true
+    },
+    weekNumber: {
+        type: DataTypes.INTEGER,
+        allowNull: true,
+        field: 'week_number'
+    },
+    dayNumber: {
+        type: DataTypes.INTEGER,
+        allowNull: true,
+        field: 'day_number'
+    },
+    lessonType: {
+        type: DataTypes.TEXT,
+        allowNull: false,
+        defaultValue: 'vocab',
+        field: 'lesson_type'
+    },
+    audioUrl: {
+        type: DataTypes.TEXT,
+        allowNull: true,
+        field: 'audio_url'
+    },
+    culturalNotes: {
+        type: DataTypes.TEXT,
+        allowNull: true,
+        field: 'cultural_notes'
+    },
+    targetMinutes: {
+        type: DataTypes.INTEGER,
+        allowNull: true,
+        field: 'target_minutes'
+    },
+    targetScorePercent: {
+        type: DataTypes.INTEGER,
+        allowNull: false,
+        defaultValue: 80,
+        field: 'target_score_percent'
+    },
+    requiresReview: {
+        type: DataTypes.BOOLEAN,
+        allowNull: false,
+        defaultValue: false,
+        field: 'requires_review'
+    },
+    createdAt: {
+        type: DataTypes.DATE,
+        allowNull: false,
+        defaultValue: DataTypes.NOW,
+        field: 'created_at'
+    }
+}, {
+    sequelize,
+    modelName: 'VocabCourseLesson',
+    tableName: 'vocab_course_lesson',
+    schema: 'community',
+    timestamps: false,
+    underscored: true
+});
+
+export default VocabCourseLesson;

backend/models/community/vocab_course_progress.js

@@ -0,0 +1,56 @@
+import { Model, DataTypes } from 'sequelize';
+import { sequelize } from '../../utils/sequelize.js';
+
+class VocabCourseProgress extends Model {}
+
+VocabCourseProgress.init({
+    id: {
+        type: DataTypes.INTEGER,
+        primaryKey: true,
+        autoIncrement: true
+    },
+    userId: {
+        type: DataTypes.INTEGER,
+        allowNull: false,
+        field: 'user_id'
+    },
+    courseId: {
+        type: DataTypes.INTEGER,
+        allowNull: false,
+        field: 'course_id'
+    },
+    lessonId: {
+        type: DataTypes.INTEGER,
+        allowNull: false,
+        field: 'lesson_id'
+    },
+    completed: {
+        type: DataTypes.BOOLEAN,
+        allowNull: false,
+        defaultValue: false
+    },
+    score: {
+        type: DataTypes.INTEGER,
+        allowNull: false,
+        defaultValue: 0
+    },
+    lastAccessedAt: {
+        type: DataTypes.DATE,
+        allowNull: true,
+        field: 'last_accessed_at'
+    },
+    completedAt: {
+        type: DataTypes.DATE,
+        allowNull: true,
+        field: 'completed_at'
+    }
+}, {
+    sequelize,
+    modelName: 'VocabCourseProgress',
+    tableName: 'vocab_course_progress',
+    schema: 'community',
+    timestamps: false,
+    underscored: true
+});
+
+export default VocabCourseProgress;

backend/models/community/vocab_grammar_exercise.js

@@ -0,0 +1,69 @@
+import { Model, DataTypes } from 'sequelize';
+import { sequelize } from '../../utils/sequelize.js';
+
+class VocabGrammarExercise extends Model {}
+
+VocabGrammarExercise.init({
+    id: {
+        type: DataTypes.INTEGER,
+        primaryKey: true,
+        autoIncrement: true
+    },
+    lessonId: {
+        type: DataTypes.INTEGER,
+        allowNull: false,
+        field: 'lesson_id'
+    },
+    exerciseTypeId: {
+        type: DataTypes.INTEGER,
+        allowNull: false,
+        field: 'exercise_type_id'
+    },
+    exerciseNumber: {
+        type: DataTypes.INTEGER,
+        allowNull: false,
+        field: 'exercise_number'
+    },
+    title: {
+        type: DataTypes.TEXT,
+        allowNull: false
+    },
+    instruction: {
+        type: DataTypes.TEXT,
+        allowNull: true
+    },
+    questionData: {
+        type: DataTypes.JSONB,
+        allowNull: false,
+        field: 'question_data'
+    },
+    answerData: {
+        type: DataTypes.JSONB,
+        allowNull: false,
+        field: 'answer_data'
+    },
+    explanation: {
+        type: DataTypes.TEXT,
+        allowNull: true
+    },
+    createdByUserId: {
+        type: DataTypes.INTEGER,
+        allowNull: false,
+        field: 'created_by_user_id'
+    },
+    createdAt: {
+        type: DataTypes.DATE,
+        allowNull: false,
+        defaultValue: DataTypes.NOW,
+        field: 'created_at'
+    }
+}, {
+    sequelize,
+    modelName: 'VocabGrammarExercise',
+    tableName: 'vocab_grammar_exercise',
+    schema: 'community',
+    timestamps: false,
+    underscored: true
+});
+
+export default VocabGrammarExercise;

backend/models/community/vocab_grammar_exercise_progress.js

@@ -0,0 +1,57 @@
+import { Model, DataTypes } from 'sequelize';
+import { sequelize } from '../../utils/sequelize.js';
+
+class VocabGrammarExerciseProgress extends Model {}
+
+VocabGrammarExerciseProgress.init({
+    id: {
+        type: DataTypes.INTEGER,
+        primaryKey: true,
+        autoIncrement: true
+    },
+    userId: {
+        type: DataTypes.INTEGER,
+        allowNull: false,
+        field: 'user_id'
+    },
+    exerciseId: {
+        type: DataTypes.INTEGER,
+        allowNull: false,
+        field: 'exercise_id'
+    },
+    attempts: {
+        type: DataTypes.INTEGER,
+        allowNull: false,
+        defaultValue: 0
+    },
+    correctAttempts: {
+        type: DataTypes.INTEGER,
+        allowNull: false,
+        defaultValue: 0,
+        field: 'correct_attempts'
+    },
+    lastAttemptAt: {
+        type: DataTypes.DATE,
+        allowNull: true,
+        field: 'last_attempt_at'
+    },
+    completed: {
+        type: DataTypes.BOOLEAN,
+        allowNull: false,
+        defaultValue: false
+    },
+    completedAt: {
+        type: DataTypes.DATE,
+        allowNull: true,
+        field: 'completed_at'
+    }
+}, {
+    sequelize,
+    modelName: 'VocabGrammarExerciseProgress',
+    tableName: 'vocab_grammar_exercise_progress',
+    schema: 'community',
+    timestamps: false,
+    underscored: true
+});
+
+export default VocabGrammarExerciseProgress;

backend/models/community/vocab_grammar_exercise_type.js

@@ -0,0 +1,36 @@
+import { Model, DataTypes } from 'sequelize';
+import { sequelize } from '../../utils/sequelize.js';
+
+class VocabGrammarExerciseType extends Model {}
+
+VocabGrammarExerciseType.init({
+    id: {
+        type: DataTypes.INTEGER,
+        primaryKey: true,
+        autoIncrement: true
+    },
+    name: {
+        type: DataTypes.TEXT,
+        allowNull: false,
+        unique: true
+    },
+    description: {
+        type: DataTypes.TEXT,
+        allowNull: true
+    },
+    createdAt: {
+        type: DataTypes.DATE,
+        allowNull: false,
+        defaultValue: DataTypes.NOW,
+        field: 'created_at'
+    }
+}, {
+    sequelize,
+    modelName: 'VocabGrammarExerciseType',
+    tableName: 'vocab_grammar_exercise_type',
+    schema: 'community',
+    timestamps: false,
+    underscored: true
+});
+
+export default VocabGrammarExerciseType;