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/community/vocab_srs_item.js

@@ -0,0 +1,94 @@
+import { Model, DataTypes } from 'sequelize';
+import { sequelize } from '../../utils/sequelize.js';
+
+class VocabSrsItem extends Model {}
+
+VocabSrsItem.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: true,
+    field: 'lesson_id'
+  },
+  itemKey: {
+    type: DataTypes.STRING(80),
+    allowNull: false,
+    field: 'item_key'
+  },
+  learning: {
+    type: DataTypes.TEXT,
+    allowNull: false
+  },
+  reference: {
+    type: DataTypes.TEXT,
+    allowNull: false
+  },
+  direction: {
+    type: DataTypes.STRING(8),
+    allowNull: false,
+    defaultValue: 'BOTH'
+  },
+  stage: {
+    type: DataTypes.INTEGER,
+    allowNull: false,
+    defaultValue: 0
+  },
+  intervalDays: {
+    type: DataTypes.INTEGER,
+    allowNull: false,
+    defaultValue: 0,
+    field: 'interval_days'
+  },
+  lastReviewedAt: {
+    type: DataTypes.DATE,
+    allowNull: true,
+    field: 'last_reviewed_at'
+  },
+  nextDueAt: {
+    type: DataTypes.DATE,
+    allowNull: false,
+    defaultValue: DataTypes.NOW,
+    field: 'next_due_at'
+  },
+  correctCount: {
+    type: DataTypes.INTEGER,
+    allowNull: false,
+    defaultValue: 0,
+    field: 'correct_count'
+  },
+  wrongCount: {
+    type: DataTypes.INTEGER,
+    allowNull: false,
+    defaultValue: 0,
+    field: 'wrong_count'
+  },
+  lapseCount: {
+    type: DataTypes.INTEGER,
+    allowNull: false,
+    defaultValue: 0,
+    field: 'lapse_count'
+  }
+}, {
+  sequelize,
+  modelName: 'VocabSrsItem',
+  tableName: 'vocab_srs_item',
+  schema: 'community',
+  timestamps: true,
+  underscored: true
+});
+
+export default VocabSrsItem;