[management] Add user approval (#4411)

This PR adds user approval functionality to the management system, allowing administrators to manually approve new users joining via domain matching. When enabled, users are blocked with pending approval status until explicitly approved by an admin.

Adds UserApprovalRequired setting to control manual user approval requirement
Introduces user approval and rejection endpoints with corresponding business logic
Prevents pending approval users from adding peers or logging in

management/server/user.go

@@ -1207,3 +1207,77 @@ func (am *DefaultAccountManager) GetCurrentUserInfo(ctx context.Context, userAut
 
 	return userWithPermissions, nil
 }
+
+// ApproveUser approves a user that is pending approval
+func (am *DefaultAccountManager) ApproveUser(ctx context.Context, accountID, initiatorUserID, targetUserID string) (*types.UserInfo, error) {
+	allowed, err := am.permissionsManager.ValidateUserPermissions(ctx, accountID, initiatorUserID, modules.Users, operations.Update)
+	if err != nil {
+		return nil, status.NewPermissionValidationError(err)
+	}
+	if !allowed {
+		return nil, status.NewPermissionDeniedError()
+	}
+
+	user, err := am.Store.GetUserByUserID(ctx, store.LockingStrengthNone, targetUserID)
+	if err != nil {
+		return nil, err
+	}
+
+	if user.AccountID != accountID {
+		return nil, status.NewUserNotFoundError(targetUserID)
+	}
+
+	if !user.PendingApproval {
+		return nil, status.Errorf(status.InvalidArgument, "user %s is not pending approval", targetUserID)
+	}
+
+	user.Blocked = false
+	user.PendingApproval = false
+
+	err = am.Store.SaveUser(ctx, user)
+	if err != nil {
+		return nil, err
+	}
+
+	am.StoreEvent(ctx, initiatorUserID, targetUserID, accountID, activity.UserApproved, nil)
+
+	userInfo, err := am.getUserInfo(ctx, user, accountID)
+	if err != nil {
+		return nil, err
+	}
+
+	return userInfo, nil
+}
+
+// RejectUser rejects a user that is pending approval by deleting them
+func (am *DefaultAccountManager) RejectUser(ctx context.Context, accountID, initiatorUserID, targetUserID string) error {
+	allowed, err := am.permissionsManager.ValidateUserPermissions(ctx, accountID, initiatorUserID, modules.Users, operations.Delete)
+	if err != nil {
+		return status.NewPermissionValidationError(err)
+	}
+	if !allowed {
+		return status.NewPermissionDeniedError()
+	}
+
+	user, err := am.Store.GetUserByUserID(ctx, store.LockingStrengthNone, targetUserID)
+	if err != nil {
+		return err
+	}
+
+	if user.AccountID != accountID {
+		return status.NewUserNotFoundError(targetUserID)
+	}
+
+	if !user.PendingApproval {
+		return status.Errorf(status.InvalidArgument, "user %s is not pending approval", targetUserID)
+	}
+
+	err = am.DeleteUser(ctx, accountID, initiatorUserID, targetUserID)
+	if err != nil {
+		return err
+	}
+
+	am.StoreEvent(ctx, initiatorUserID, targetUserID, accountID, activity.UserRejected, nil)
+
+	return nil
+}