[#20] 번개모임 푸시알림(fcm) 추가, 메시지큐 추가

schemas/ChatRoomParticipants.js

-// schemas/ChatRoomParticipant.js
-
-const mongoose = require('mongoose');
-
-const ChatRoomParticipantSchema = new mongoose.Schema({
-  chat_room_id: {
-    type: mongoose.Schema.Types.ObjectId,
-    ref: 'ChatRoom',
-    required: true,
-  },
-  user_id: {
-    type: Number, // SQL의 Users 테이블 ID 참조
-    required: true,
-  },
-  left_at: {
-    type: Date,
-    default: null,
-  },
-}, {
-  timestamps: { createdAt: 'joined_at', updatedAt: false },
-});
-
-module.exports = mongoose.model('ChatRoomParticipant', ChatRoomParticipantSchema);