🔧 refactor: Add and use PrincipalType Enum

- Replaced string literals for principal types ('user', 'group', 'public') with the new PrincipalType enum across various models, services, and tests for improved type safety and consistency.
- Updated permission handling in multiple files to utilize the PrincipalType enum, enhancing maintainability and reducing potential errors.
- Ensured all relevant tests reflect these changes to maintain coverage and functionality.

api/server/routes/files/files.agents.test.js

@@ -2,9 +2,9 @@ const express = require('express');
 const request = require('supertest');
 const mongoose = require('mongoose');
 const { v4: uuidv4 } = require('uuid');
-const { MongoMemoryServer } = require('mongodb-memory-server');
 const { createMethods } = require('@librechat/data-schemas');
-const { AccessRoleIds, ResourceType } = require('librechat-data-provider');
+const { MongoMemoryServer } = require('mongodb-memory-server');
+const { AccessRoleIds, ResourceType, PrincipalType } = require('librechat-data-provider');
 const { createAgent } = require('~/models/Agent');
 const { createFile } = require('~/models/File');
 
@@ -185,7 +185,7 @@ describe('File Routes - Agent Files Endpoint', () => {
       // Grant EDIT permission to user on the agent using PermissionService
       const { grantPermission } = require('~/server/services/PermissionService');
       await grantPermission({
-        principalType: 'user',
+        principalType: PrincipalType.USER,
         principalId: otherUserId,
         resourceType: ResourceType.AGENT,
         resourceId: agent._id,
@@ -240,7 +240,7 @@ describe('File Routes - Agent Files Endpoint', () => {
       // Grant only VIEW permission to user on the agent
       const { grantPermission } = require('~/server/services/PermissionService');
       await grantPermission({
-        principalType: 'user',
+        principalType: PrincipalType.USER,
         principalId: otherUserId,
         resourceType: ResourceType.AGENT,
         resourceId: agent._id,