fix(auth): replace mongoose model references with new function imports

- Updated AuthController, checkBan middleware, localStrategy, and openidStrategy to use new function imports for user operations.
- Removed unused mongoose imports to streamline the codebase.
- Enhanced consistency across user-related operations by utilizing the centralized methods for user management.

api/server/middleware/checkBan.js

@@ -1,14 +1,12 @@
 const { Keyv } = require('keyv');
 const uap = require('ua-parser-js');
-const mongoose = require('mongoose');
 const { logger } = require('@librechat/data-schemas');
 const { ViolationTypes } = require('librechat-data-provider');
 const { isEnabled, removePorts } = require('~/server/utils');
 const keyvMongo = require('~/cache/keyvMongo');
 const denyRequest = require('./denyRequest');
 const { getLogStores } = require('~/cache');
-
-const User = require('~/db/models').User;
+const { findUser } = require('~/models');
 
 const banCache = new Keyv({ store: keyvMongo, namespace: ViolationTypes.BAN, ttl: 0 });
 const message = 'Your account has been temporarily banned due to violations of our service.';
@@ -59,7 +57,7 @@ const checkBan = async (req, res, next = () => {}) => {
     let userId = req.user?.id ?? req.user?._id ?? null;
 
     if (!userId && req?.body?.email) {
-      const user = await User.findUser({ email: req.body.email }, '_id');
+      const user = await findUser({ email: req.body.email }, '_id');
       userId = user?._id ? user._id.toString() : userId;
     }