Add calendar feature: Integrate calendarRouter and CalendarEvent model, enhance CalendarView with API interactions for event management, and update localization files for error handling in both English and German. This update improves the calendar functionality and user experience.

backend/models/community/calendar_event.js

@@ -0,0 +1,86 @@
+import { Model, DataTypes } from 'sequelize';
+import { sequelize } from '../../utils/sequelize.js';
+
+class CalendarEvent extends Model { }
+
+CalendarEvent.init({
+    id: {
+        type: DataTypes.INTEGER,
+        primaryKey: true,
+        autoIncrement: true
+    },
+    userId: {
+        type: DataTypes.INTEGER,
+        allowNull: false,
+        references: {
+            model: 'user',
+            key: 'id'
+        }
+    },
+    title: {
+        type: DataTypes.STRING(255),
+        allowNull: false
+    },
+    description: {
+        type: DataTypes.TEXT,
+        allowNull: true
+    },
+    categoryId: {
+        type: DataTypes.STRING(50),
+        allowNull: false,
+        defaultValue: 'personal',
+        comment: 'Category key: personal, work, family, health, birthday, holiday, reminder, other'
+    },
+    startDate: {
+        type: DataTypes.DATEONLY,
+        allowNull: false
+    },
+    endDate: {
+        type: DataTypes.DATEONLY,
+        allowNull: true,
+        comment: 'End date for multi-day events, null means same as startDate'
+    },
+    startTime: {
+        type: DataTypes.TIME,
+        allowNull: true,
+        comment: 'Start time, null for all-day events'
+    },
+    endTime: {
+        type: DataTypes.TIME,
+        allowNull: true,
+        comment: 'End time, null for all-day events'
+    },
+    allDay: {
+        type: DataTypes.BOOLEAN,
+        allowNull: false,
+        defaultValue: false
+    },
+    createdAt: {
+        type: DataTypes.DATE,
+        defaultValue: DataTypes.NOW
+    },
+    updatedAt: {
+        type: DataTypes.DATE,
+        defaultValue: DataTypes.NOW
+    }
+}, {
+    sequelize,
+    modelName: 'CalendarEvent',
+    tableName: 'calendar_event',
+    schema: 'community',
+    timestamps: true,
+    underscored: true,
+    indexes: [
+        {
+            fields: ['user_id']
+        },
+        {
+            fields: ['user_id', 'start_date']
+        },
+        {
+            fields: ['user_id', 'start_date', 'end_date']
+        }
+    ]
+});
+
+export default CalendarEvent;