feat: Add granular role-based permissions system with Entra ID integration

- Implement RBAC with viewer/editor/owner roles using bitwise permissions
      - Add AccessRole, AclEntry, and Group models for permission management
      - Create PermissionService for core permission logic and validation
      - Integrate Microsoft Graph API for Entra ID user/group search
      - Add middleware for resource access validation with custom ID resolvers
      - Implement bulk permission updates with transaction support
      - Create permission management UI with people picker and role selection
      - Add public sharing capabilities for resources
      - Include database migration for existing agent ownership
      - Support hybrid local/Entra ID identity management
      - Add comprehensive test coverage for all new services

chore: Update @librechat/data-schemas to version 0.0.9 and export common module in index.ts

fix: Update userGroup tests to mock logger correctly and change principalId expectation from null to undefined

api/server/middleware/accessResources/canAccessAgentResource.js

@@ -0,0 +1,58 @@
+const { getAgent } = require('~/models/Agent');
+const { canAccessResource } = require('./canAccessResource');
+
+/**
+ * Agent ID resolver function
+ * Resolves custom agent ID (e.g., "agent_abc123") to MongoDB ObjectId
+ *
+ * @param {string} agentCustomId - Custom agent ID from route parameter
+ * @returns {Promise<Object|null>} Agent document with _id field, or null if not found
+ */
+const resolveAgentId = async (agentCustomId) => {
+  return await getAgent({ id: agentCustomId });
+};
+
+/**
+ * Agent-specific middleware factory that creates middleware to check agent access permissions.
+ * This middleware extends the generic canAccessResource to handle agent custom ID resolution.
+ *
+ * @param {Object} options - Configuration options
+ * @param {number} options.requiredPermission - The permission bit required (1=view, 2=edit, 4=delete, 8=share)
+ * @param {string} [options.resourceIdParam='id'] - The name of the route parameter containing the agent custom ID
+ * @returns {Function} Express middleware function
+ *
+ * @example
+ * // Basic usage for viewing agents
+ * router.get('/agents/:id',
+ *   canAccessAgentResource({ requiredPermission: 1 }),
+ *   getAgent
+ * );
+ *
+ * @example
+ * // Custom resource ID parameter and edit permission
+ * router.patch('/agents/:agent_id',
+ *   canAccessAgentResource({
+ *     requiredPermission: 2,
+ *     resourceIdParam: 'agent_id'
+ *   }),
+ *   updateAgent
+ * );
+ */
+const canAccessAgentResource = (options) => {
+  const { requiredPermission, resourceIdParam = 'id' } = options;
+
+  if (!requiredPermission || typeof requiredPermission !== 'number') {
+    throw new Error('canAccessAgentResource: requiredPermission is required and must be a number');
+  }
+
+  return canAccessResource({
+    resourceType: 'agent',
+    requiredPermission,
+    resourceIdParam,
+    idResolver: resolveAgentId,
+  });
+};
+
+module.exports = {
+  canAccessAgentResource,
+};