feat(vocab): implement SRS features and enhance vocabulary management

- Added new endpoints in vocabController for retrieving SRS due items and reviewing SRS items, improving spaced repetition support.
- Updated vocabService to handle SRS item creation and scheduling, ensuring effective tracking of vocabulary exposure.
- Enhanced vocabRouter with new routes for SRS functionalities, facilitating user interaction with spaced repetition features.
- Modified VocabPracticeDialog and VocabCourseView to integrate SRS due items, providing users with timely review opportunities.
- Updated translations and UI elements to reflect new SRS features, enhancing user experience and accessibility.

backend/models/associations.js

@@ -126,6 +126,7 @@ 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';
+import VocabSrsItem from './community/vocab_srs_item.js';
 import CalendarEvent from './community/calendar_event.js';
 import Campaign from './match3/campaign.js';
 import Match3Level from './match3/level.js';
@@ -1176,6 +1177,13 @@ export default function setupAssociations() {
   User.hasMany(VocabGrammarExerciseProgress, { foreignKey: 'userId', as: 'grammarExerciseProgress' });
   VocabGrammarExerciseProgress.belongsTo(VocabGrammarExercise, { foreignKey: 'exerciseId', as: 'exercise' });
   VocabGrammarExercise.hasMany(VocabGrammarExerciseProgress, { foreignKey: 'exerciseId', as: 'progress' });
+
+  VocabSrsItem.belongsTo(User, { foreignKey: 'userId', as: 'user' });
+  User.hasMany(VocabSrsItem, { foreignKey: 'userId', as: 'vocabSrsItems' });
+  VocabSrsItem.belongsTo(VocabCourse, { foreignKey: 'courseId', as: 'course' });
+  VocabCourse.hasMany(VocabSrsItem, { foreignKey: 'courseId', as: 'srsItems' });
+  VocabSrsItem.belongsTo(VocabCourseLesson, { foreignKey: 'lessonId', as: 'lesson' });
+  VocabCourseLesson.hasMany(VocabSrsItem, { foreignKey: 'lessonId', as: 'srsItems' });
   
   // Calendar associations
   CalendarEvent.belongsTo(User, { foreignKey: 'userId', as: 'user' });